Electrically enhanced retrieval of material from vessel lumens

ABSTRACT

Retrieval of material from vessel lumens can be improved by electrically enhancing attachment of the material to the thrombectomy system. The system can include a catheter having a distal portion configured to be positioned adjacent to a thrombus in a blood vessel, an electrode disposed at the distal portion of the catheter, and an interventional element configured to be delivered through a lumen of the catheter. The electrode and the interventional element are each configured to be electrically coupled to an extracorporeal power supply.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 16/024,367, filed Jun. 29, 2018, which claims the benefit ofpriority to U.S. Provisional Application No. 62/688,636, filed Jun. 22,2018, the contents of each of which are incorporated by reference hereinin their entirety.

TECHNICAL FIELD

The present technology relates generally to devices and methods forremoving obstructions from body lumens. Some embodiments of the presenttechnology relate to devices and methods for electrically enhancedremoval of clot material from blood vessels.

BACKGROUND

Many medical procedures use medical device(s) to remove an obstruction(such as clot material) from a body lumen, vessel, or other organ. Aninherent risk in such procedures is that mobilizing or otherwisedisturbing the obstruction can potentially create further harm if theobstruction or a fragment thereof dislodges from the retrieval device.If all or a portion of the obstruction breaks free from the device andflows downstream, it is highly likely that the free material will becometrapped in smaller and more tortuous anatomy. In many cases, thephysician will no longer be able to use the same retrieval device toagain remove the obstruction because the device may be too large and/orimmobile to move the device to the site of the new obstruction.

Procedures for treating ischemic stroke by restoring flow within thecerebral vasculature are subject to the above concerns. The brain relieson its arteries and veins to supply oxygenated blood from the heart andlungs and to remove carbon dioxide and cellular waste from brain tissue.Blockages that interfere with this blood supply eventually cause thebrain tissue to stop functioning. If the disruption in blood occurs fora sufficient amount of time, the continued lack of nutrients and oxygencauses irreversible cell death. Accordingly, it is desirable to provideimmediate medical treatment of an ischemic stroke.

To access the cerebral vasculature, a physician typically advances acatheter from a remote part of the body (typically a leg) through theabdominal vasculature and into the cerebral region of the vasculature.Once within the cerebral vasculature, the physician deploys a device forretrieval of the obstruction causing the blockage. Concerns aboutdislodged obstructions or the migration of dislodged fragments increasesthe duration of the procedure at a time when restoration of blood flowis paramount. Furthermore, a physician might be unaware of one or morefragments that dislodge from the initial obstruction and cause blockageof smaller more distal vessels.

Many physicians currently perform thrombectomies (i.e. clot removal)with stents to resolve ischemic stroke. Typically, the physician deploysa stent into the clot in an attempt to push the clot to the side of thevessel and re-establish blood flow. Tissue plasminogen activator (“tPA”)is often injected into the bloodstream through an intravenous line tobreak down a clot. However, it takes time for the tPA to reach the clotbecause the tPA must travel through the vasculature and only begins tobreak up the clot once it reaches the clot material. tPA is also oftenadministered to supplement the effectiveness of the stent. Yet, ifattempts at clot dissolution are ineffective or incomplete, thephysician can attempt to remove the stent while it is expanded againstor enmeshed within the clot. In doing so, the physician must effectivelydrag the clot through the vasculature, in a proximal direction, into aguide catheter located within vessels in the patient's neck (typicallythe carotid artery). While this procedure has been shown to be effectivein the clinic and easy for the physician to perform, there remain somedistinct disadvantages to using this approach.

For example, one disadvantage is that the stent may not sufficientlyretain the clot as it pulls the clot to the catheter. In such a case,some or all of the clot might remain in the vasculature. Another risk isthat, as the stent mobilizes the clot from the original blockage site,the clot might not adhere to the stent as the stent is withdrawn towardthe catheter. This is a particular risk when passing throughbifurcations and tortuous anatomy. Furthermore, blood flow can carry theclot (or fragments of the clot) into a branching vessel at abifurcation. If the clot is successfully brought to the end of the guidecatheter in the carotid artery, yet another risk is that the clot may be“stripped” or “sheared” from the stent as the stent enters the guidecatheter.

In view of the above, there remains a need for improved devices andmethods that can remove occlusions from body lumens and/or vessels.

SUMMARY

Mechanical thrombectomy (i.e., clot-grabbing and removal) has beeneffectively used for treatment of ischemic stroke. Although most clotscan be retrieved in a single pass attempt, there are instances in whichmultiple attempts are needed to fully retrieve the clot and restoreblood flow through the vessel. Additionally, there exist complicationsdue to detachment of the clot from the interventional element during theretrieval process as the interventional element and clot traversethrough tortuous intracranial vascular anatomy. For example, thedetached clot or clot fragments can obstruct other arteries leading tosecondary strokes. The failure modes that contribute to clot releaseduring retrieval are: (a) boundary conditions at bifurcations; (b)changes in vessel diameter; and (c) vessel tortuosity, amongst others.

Certain blood components, such as platelets and coagulation proteins,display negative electrical charges. The treatment systems of thepresent technology provide an interventional element and a currentgenerator configured to positively charge the interventional elementduring one or more stages of a thrombectomy procedure. For example, thecurrent generator may apply a constant or pulsatile direct current (DC)to the interventional element. The positively charged interventionalelement attracts negatively charged blood components, thereby improvingattachment of the thrombus to the interventional element and reducingthe number of device passes or attempts necessary to fully retrieve theclot. In some aspects of the present technology, the treatment systemincludes a core member extending between the current generator and theinterventional element. A delivery electrode may be integrated into thecore member, and the treatment system further includes a returnelectrode that may be disposed at a number of different locations. Forexample, the return electrode can be a needle, a grounding pad, aconductive element carried by a one or more catheters of the treatmentsystem, a guide wire, and/or any other suitable conductive elementconfigured to complete an electrical circuit with the delivery electrodeand the extracorporeally positioned current generator. When theinterventional element is placed in the presence of blood (or any otherelectrolytic medium) and voltage is applied at the terminals of thecurrent generator, current flows along the core member to theinterventional element, through the blood, and to the return electrode,thereby positively charging at least a portion of the interventionalelement and adhering clot material thereto.

While applying a current to positively charge the interventional elementcan improve attachment of the thrombus to the interventional element,the inventors have discovered particularly effective waveforms and powerdelivery parameters for promoting thrombus attachment. It is importantto provide sufficient current and power to enhance clot-adhesion withoutablating tissue or generating new clots (i.e., the delivered powershould not be significantly thrombogenic). The clot-adhesion effectappears to be driven by the peak current of the delivered electricalsignal. Periodic (e.g., pulse-width modulated or pulsed direct current)waveforms can advantageously provide the desired peak current withoutdelivering excessive total energy. In particular, non-square periodicwaveforms can be especially effective in providing the desired peakcurrent without delivering excessive total energy or electrical chargeto the interventional element. In some embodiments, the overall chargedelivered can be between about 30-1200 mC, the total energy deliveredcan be between about 120-24,000 mJ, and/or the peak current deliveredcan be between about 0.5-5 mA. In at least some embodiments, theduration of energy delivery can be between 30 seconds and 5 minutes, andin some embodiments no more than 2 minutes.

The treatment systems and methods of the present technology can furtherimprove adhesion of the clot to the interventional element by varyingfeatures of the interventional element. For example, in someembodiments, some or all of the interventional element can be coatedwith one or more highly conductive materials, such as gold, to improveclot adhesion. In some aspects of the present technology, a workinglength of the interventional element may be coated with the conductivematerial while a non-working length of the interventional element may becoated with an insulative material.

Treatment systems and methods disclosed herein may also improve clotadhesion by modifying the environment at the treatment site. Forexample, the inventors have observed that blood flow at the treatmentsite reduces adhesion forces between clot material and theinterventional element, even when the interventional element ispositively charged. To address this loss of adhesion, the presenttechnology provides systems and methods for arresting blood flow at thetreatment site at least while supplying electrical energy to thetreatment site. In addition, the present technology provides systems andmethods for infusing certain fluids (such as saline and/or contrast) atthe treatment site at least during energy delivery to improveconductivity at the treatment site for electrically enhanced clotadhesion.

Many of the treatment systems of the present technology include anaspiration catheter for applying negative pressure at the treatment siteto secure the clot against a distal portion of the aspiration catheter(and/or other component of the treatment system). Aspiration also helpscapture any newly formed clots to reduce the risk of downstreamembolism. Suction may be applied before, during, and/or after supplyingelectrical energy to the interventional element. In some embodiments, adistal portion of the aspiration catheter may be configured forelectrically enhanced clot adhesion such that clot engagement andretrieval may be performed without a separate interventional element.For example, in some aspects of the technology, the aspiration cathetermay include a delivery electrode at its distal tip that is configured tobe positively charged by the current generator. A return electrode maybe disposed at a number of different locations, such as the aspirationcatheter or another component of the treatment system (such as a guidecatheter). Securement of the clot to the aspiration catheter via suctionmay be enhanced by the additional adhesion forces generated when thedelivery electrode is positively charged.

The present technology is illustrated, for example, according to variousaspects described below. Various examples of aspects of the presenttechnology are described as numbered clauses (1, 2, 3, etc.) forconvenience. These are provided as examples and do not limit the presenttechnology. It is noted that any of the dependent clauses may becombined in any combination, and placed into a respective independentclause, e.g., clause (1, 23, 35, etc.). The other clauses can bepresented in a similar manner.

Clause 1. A thrombectomy system, comprising:

-   -   a power source having a positive terminal;    -   an elongated member having a proximal end coupled to the power        source and a distal end configured to be positioned within a        blood vessel at or near a thrombus; and    -   an interventional element carried at the distal end of the        elongated member and coupled to the positive terminal of the        power source, wherein the interventional element includes a        first metallic material and a second metallic material disposed        on the first metallic material along at least a portion of the        interventional element, and wherein the power source is        configured to deliver a current to the interventional element to        positively charge the interventional element and promote        adhesion of the thrombus thereto.

Clause 2. The thrombectomy system of Clause 1, wherein the power sourceis configured to be extracorporeally positioned while the interventionalelement is positioned at or near the thrombus.

Clause 3. The thrombectomy system of Clause 1 or Clause 2, wherein anelectrical conductivity of the second metallic material is greater thanan electrical conductivity of the first metallic material.

Clause 4. The thrombectomy system of any one of Clauses 1 to 3, whereinthe first metallic material is a superelastic alloy and the secondmetallic material is gold.

Clause 5. The thrombectomy system of any one of Clauses 1 to 4, whereinthe first metallic material has a surface including an outward-facingportion that faces away from a central lumen of the interventionalelement, and wherein the second metallic material is disposed on thefirst metallic material only at the outward-facing portion and not at aremaining portion of the surface.

Clause 6. The thrombectomy system of any one of Clauses 1 to 5, whereinthe interventional element comprises a working length portion and anon-working length portion, the working length portion being configuredto interlock, capture, and/or engage a thrombus.

Clause 7. The thrombectomy system of Clause 6, wherein a distal terminusof the working length portion is proximal of a distal terminus of theinterventional element.

Clause 8. The thrombectomy system of Clause 6 or Clause 7, wherein theworking length portion is spaced apart from a distal terminus of theinterventional element.

Clause 9. The thrombectomy system of any one of Clauses 6 to 8, whereinthe non-working length portion is disposed between a distal end of theelongated member and a proximal end of the working length portion.

Clause 10. The thrombectomy system of any one of Clauses 6 to 9, whereinthe second metallic material has a greater conductivity than the firstmetallic material and is disposed on the first metallic material onlyalong the working length portion of the interventional element and notalong the non-working length portion.

Clause 11. The thrombectomy system of any one of Clauses 6 to 10,wherein the second metallic material has a greater conductivity than thefirst metallic material and is disposed on the first metallic materialonly along the working length portion of the interventional element andnot along (i) the non-working length portion and (ii) a distal-mostregion of the interventional element.

Clause 12. The thrombectomy system of any one of Clauses 6 to 11,wherein the non-working length portion is covered by a non-conductiveand/or insulative material such that the non-working length portion isnot in electrical contact with the surrounding media when theinterventional element is deployed within a blood vessel.

Clause 13. The thrombectomy system of any one of Clauses 6 to 11,wherein the non-working length portion and a region of theinterventional element distal of the working length portion are coveredby a non-conductive and/or insulative material such that the non-workinglength portion and the region are not in electrical contact with thesurrounding media when the interventional element is deployed within ablood vessel.

Clause 14. The thrombectomy system of any one of Clauses 6 to 11,wherein the second metallic material is selectively disposed on thefirst metallic material such that the delivered current is concentratedalong the working length portion.

Clause 15. The thrombectomy system of any one of Clauses 1 to 14,wherein the power source is configured to deliver direct current to theinterventional element.

Clause 16. The thrombectomy system of any one of Clauses 1 to 15,wherein the power source is configured to deliver pulsatile current tothe interventional element.

Clause 17. The thrombectomy system of any one of Clauses 1 to 16,wherein the current is a constant current having an amplitude of betweenabout 0.5 mA and about 5 mA.

Clause 18. The thrombectomy system of any one of Clauses 1 to 17,wherein the interventional element comprises a thrombectomy device.

Clause 19. The thrombectomy system of any one of Clauses 1 to 18,wherein the interventional element comprises a stent retriever.

Clause 20. The thrombectomy system of any one of Clauses 1 to 19,wherein the interventional element comprises a removal device.

Clause 21. The thrombectomy system of any one of Clauses 1 to 20,wherein the interventional element is a mesh.

Clause 22. The thrombectomy system of any one of Clauses 1 to 21,wherein the interventional element is a laser-cut stent.

Clause 23. A thrombectomy system, comprising:

-   -   a power source having a positive terminal;    -   a first catheter;    -   a second catheter configured to be slidably received through a        lumen of the first catheter;    -   an elongated member configured to be slidably received through a        lumen of the second catheter, the elongated member having a        proximal end coupled to the power source and a distal end        configured to be positioned within a blood vessel at or near a        thrombus; and    -   an interventional element carried at the distal end of the        elongated member and coupled to the positive terminal of the        power source, wherein the interventional element includes a        first metallic material and a second metallic material disposed        on the first metallic material along at least a portion of the        interventional element, and wherein the power source is        configured to deliver a current to the interventional element to        positively charge the interventional element and promote        adhesion of the thrombus thereto.

Clause 24. The thrombectomy system of Clause 23, wherein the firstcatheter includes a flow arrest element configured to expand within thevessel lumen and at least partially arrest blood flow proximal of thethrombus.

Clause 25. The thrombectomy system Clause 23 or Clause 24, wherein thefirst catheter is a guide catheter and the second catheter is amicrocatheter.

Clause 26. The thrombectomy system of any one of Clauses 23 to 25,wherein the thrombectomy system further includes a third catheterconfigured to be slidably received through the lumen of the firstcatheter.

Clause 27. The thrombectomy system of Clause 26, wherein the secondcatheter is configured to be slidably received within a lumen of thesecond catheter.

Clause 28. The thrombectomy system of Clause 26, wherein the firstcatheter is a guide catheter and the third catheter is a distal accesscatheter.

Clause 29. The thrombectomy system of Clause 26, wherein the firstcatheter is a guide catheter, the second catheter is a microcatheter,and the third catheter is a distal access catheter.

Clause 30. The thrombectomy system of Clause 26, wherein the thirdcatheter is an aspiration catheter.

Clause 31. The thrombectomy system of Clause 26, wherein the firstcatheter is a balloon guide catheter and the third catheter is a distalaccess catheter.

Clause 32. The thrombectomy system Clause 26, wherein the first catheteris a guide catheter and the third catheter is a distal access catheter,wherein the distal access catheter includes a flow arrest elementconfigured to expand within the vessel lumen and at least partiallyarrest blood flow proximal of the thrombus.

Clause 33. The thrombectomy system of Clause 32, wherein the distalaccess catheter is an aspiration catheter.

Clause 34. The thrombectomy system of any one of Clauses 26 to 33,wherein:

-   -   the first catheter includes a flow arrest element configured to        expand within the vessel lumen and at least partially arrest        blood flow proximal of the thrombus, and    -   the third catheter is an aspiration catheter configured to apply        negative pressure at the treatment site.

Clause 35. A method, comprising:

-   -   intravascularly delivering an interventional element to a        treatment site within a blood vessel, wherein the interventional        element comprises a first metallic material and a second        metallic material disposed on the first metallic material; and    -   while the interventional element is positioned at the treatment        site, producing a positive charge along at least a portion of        the interventional element via a power source coupled to the        interventional element at an extracorporeal location.

Clause 36. The method of Clause 35, further comprising concentrating thepositive charge along a working length of the interventional element,wherein a proximal end of the working length is distal of a proximal endof the interventional element and a distal end of the working length isproximal of a distal end of the interventional element.

Clause 37. The method of any one of Clauses 35 to 36, wherein producinga positive charge includes delivering a direct current to theinterventional element from the power source.

Clause 38. The method of any one of Clauses 35 to 37, wherein producinga positive charge includes delivering a pulsatile current to theinterventional element from the power source.

Clause 39. The method of any one of Clauses 35 to 38, wherein anelectrical conductivity of the second metallic material is greater thanan electrical conductivity of the first metallic material.

Clause 40. The method of any one of Clauses 35 to 39, wherein the secondmetallic material is gold.

Clause 41. The method of any one of Clauses 35 to 40, wherein producinga positive charge includes delivering a current to the interventionalelement, the current having an amplitude of between about 0.5 mA andabout 5 mA.

Clause 42. The method of any one of Clauses 35 to 41, wherein producinga positive charge includes delivering a current to the interventionalelement, the current having an amplitude of about 2 mA.

Clause 43. The method of any one of Clauses 35 to 42, wherein theinterventional element comprises a thrombectomy device.

Clause 44. The method of any one of Clauses 35 to 43, wherein theinterventional element comprises a stent retriever.

Clause 45. The method of any one of Clauses 35 to 44, wherein theinterventional element comprises a removal device.

Clause 46. The method of any one of Clauses 35 to 45, wherein theinterventional element is a laser-cut stent or a mesh.

Clause 47. A method, comprising:

-   -   intravascularly delivering an interventional element to a        treatment site within a blood vessel at or near a thrombus; and    -   while the interventional element is positioned at the treatment        site and engaging the thrombus: (a) delivering a fluid to the        treatment site, and (b) while at least some of the fluid is        being delivered, applying a positive charge to the        interventional element, thereby promoting adhesion of the        thrombus to the interventional element.

Clause 48. The method of Clause 47, wherein an ion concentration of thefluid is greater than an ion concentration of blood.

Clause 49. The method of any one of Clauses 47 to 48, wherein the fluidis saline.

Clause 50. The method of any one of Clauses 47 to 48, wherein the fluidis contrast.

Clause 51. The method of any one of Clauses 47 to 50, wherein deliveringthe fluid to the treatment site increases an electrical conductivity atthe treatment site.

Clause 52. The method of any one of Clauses 47 to 51, wherein deliveringthe fluid occurs while blood is flowing at the treatment site.

Clause 53. The method of any one of Clauses 47 to 51, wherein deliveringthe fluid occurs while blood flow is partially arrested at the treatmentsite.

Clause 54. The method of any one of Clauses 47 to 51, wherein deliveringthe fluid occurs while blood flow is completely arrested at thetreatment site.

Clause 55. The method of any one of Clauses 47 to 54, further comprisingexpanding a flow arrest element within the blood vessel proximal of thetreatment site before or while delivering the fluid.

Clause 56. The method of any one of Clauses 47 to 55, wherein theinterventional element includes a first material and a second materialdisposed on the first material along at least a portion of theinterventional element, wherein the second material is different thanthe first material.

Clause 57. The method of any one of Clauses 47 to 55, wherein theinterventional element includes a first metallic material and a secondmetallic material disposed on the first metallic material along at leasta portion of the interventional element, and wherein a conductivity ofthe second metallic material is greater than a conductivity of the firstmetallic material.

Clause 58. The method of Clause 57, wherein the second metallic materialis gold.

Clause 59. The method of any one of Clauses 47 to 58, wherein applying apositive charge includes delivering an electric current to theinterventional element from a power source positioned at anextracorporeal location.

Clause 60. The method of Clause 59, wherein the current is deliveredwhile the interventional element is positioned at the treatment site.

Clause 61. The method of any one of Clauses 59 to 60, wherein thecurrent has an amplitude of between about 0.5 mA and about 5 mA.

Clause 62. The method of any one of Clauses 59 to 61, wherein thecurrent is a direct current.

Clause 63. The method of any one of Clauses 59 to 62, wherein theamplitude of the current remains generally constant.

Clause 64. The method of any one of Clauses 59 to 63, wherein thecurrent is delivered for at least 30 seconds, at least 1 minute, or atleast 2 minutes.

Clause 65. The method of any one of Clauses 47 to 64, wherein theinterventional element comprises a thrombectomy device.

Clause 66. The method of any one of Clauses 47 to 65, wherein theinterventional element comprises a stent retriever.

Clause 67. The method of any one of Clauses 47 to 66, wherein theinterventional element comprises a removal device.

Clause 68. The method of any one of Clauses 47 to 67, wherein theinterventional element is a mesh.

Clause 69. The method of any one of Clauses 47 to 68, wherein theinterventional element is a laser-cut stent.

Clause 70. The method of any one of Clauses 47 to 69, wherein the fluidis delivered through a distal access catheter.

Clause 71. The method of any one of Clauses 47 to 70, wherein the fluidis a liquid.

Clause 72. A method, comprising:

-   -   intravascularly delivering thrombectomy device to a treatment        site within a blood vessel at or near a thrombus;    -   positioning a catheter at the treatment site such that a distal        end of the catheter is proximal of the thrombus; and    -   while the thrombectomy device is positioned at the treatment        site and engaging the thrombus: (a) delivering a fluid through        the catheter to the treatment site, wherein delivering the fluid        increases an electrical conductivity at the treatment site;        and (b) while at least some of the fluid is being delivered,        delivering current to the thrombectomy device, thereby promoting        adhesion of the thrombus to the thrombectomy device.

Clause 73. The method of Clause 72, wherein an ion concentration of thefluid is greater than an ion concentration of blood.

Clause 74. The method of any one of Clauses 72 to 73, wherein the fluidis saline.

Clause 75. The method of any one of Clauses 72 to 73, wherein the fluidis contrast.

Clause 76. The method of any one of Clauses 72 to 74, wherein deliveringthe fluid occurs while blood is flowing at the treatment site.

Clause 77. The method of any one of Clauses 72 to 74, wherein deliveringthe fluid occurs while blood flow is partially arrested at the treatmentsite.

Clause 78. The method of any one of Clauses 72 to 74, wherein deliveringthe fluid occurs while blood flow is completely arrested at thetreatment site.

Clause 79. The method of any one of Clauses 72 to 78, wherein deliveringcurrent to the thrombectomy device positively charges the thrombectomydevice.

Clause 80. The method of any one of Clauses 72 to 79, wherein thethrombectomy device comprises a braid.

Clause 81. The method of any one of Clauses 72 to 80, wherein thethrombectomy device comprises a stent retriever.

Clause 82. The method of any one of Clauses 72 to 81, wherein thethrombectomy device comprises a removal device.

Clause 83. The method of any one of Clauses 72 to 82, wherein thethrombectomy device is a mesh.

Clause 84. The method of any one of Clauses 72 to 83, wherein thethrombectomy device is a laser-cut stent.

Clause 85. A thrombectomy system, comprising:

-   -   a catheter having a distal portion configured to be positioned        adjacent to a thrombus in a blood vessel;    -   an electrode disposed at the distal portion of the catheter, the        electrode configured to be electrically coupled to an        extracorporeal power supply; and    -   an interventional element configured to be delivered through a        lumen of the catheter, the interventional element configured to        be electrically coupled to the extracorporeal power supply.

Clause 86. The system of Clause 85, wherein the electrode is inelectrical communication with a conductive lead extending proximallyalong the catheter.

Clause 87. The system of Clause 86, wherein the conductive lead isdisposed within a wall of the catheter.

Clause 88. The system of Clause 86, wherein the conductive lead isdisposed along an external surface of the catheter.

Clause 89. The system of any one of Clauses 85 to 88, wherein theelectrode comprises a conductive band extending at least partiallycircumferentially around the distal portion of the catheter.

Clause 90. The system of Clause 89, wherein the conductive band isdisposed on an inner surface of the catheter.

Clause 91. The system of Clause 89, wherein the conductive band isdisposed on an outer surface of the catheter.

Clause 92. The system of any one of Clauses 85 to 91, wherein theelectrode comprises a stent engaged with an inner surface of thecatheter.

Clause 93. The system of any one of Clauses 85 to 92, wherein thecatheter comprises an aspiration catheter.

Clause 94. The system of any one of Clauses 85 to 93, wherein thecatheter comprises a distal access catheter.

Clause 95. The system of any one of Clauses 85 to 93, wherein thecatheter comprises a guide catheter.

Clause 96. The system of any one of Clauses 85 to 93, wherein thecatheter comprises a balloon guide catheter.

Clause 97. The system of any one of Clauses 85 to 96, wherein thecatheter is a first catheter and the system further comprises a secondcatheter, wherein the first catheter is configured to be slidablydisposed within a lumen of the second catheter.

Clause 98. The system of any one of Clauses 85 to 96, wherein thecatheter is a first catheter and the system further comprises a secondcatheter, wherein the second catheter is configured to be slidablydisposed within a lumen of the first catheter.

Clause 99. The system of any one of Clauses 85 to 98, wherein thecatheter is a microcatheter.

Clause 100. The system of any one of Clauses 85 to 96, wherein thecatheter is a first catheter and the system further comprises a secondcatheter and a third catheter, wherein the first catheter is configuredto be slidably disposed within a lumen of the second catheter, and thesecond catheter is configured to be slidably disposed within a lumen ofthe third catheter.

Clause 101. The system of any one of Clauses 85 to 100, wherein theelectrode comprises a conductive band extending at least partiallycircumferentially around the distal portion of the catheter.

Clause 102. The system of Clause 101, wherein the conductive band isdisposed on an inner surface of the catheter.

Clause 103. The system of Clause 101, wherein the conductive band isdisposed on an outer surface of the catheter.

Clause 104. The system of any one of Clauses 85 to 103, furthercomprising a suction source configured to supply negative pressurethrough the catheter to aspirate a region adjacent to the distal portionof the catheter.

Clause 105. The system of any one of Clauses 85 to 104, wherein thecatheter is an aspiration catheter having a proximal portion configuredto be fluidically coupled to a suction source.

Clause 106. The system of any one of Clauses 85 to 105, furthercomprising a power supply having positive and negative terminals, theelectrode being coupled to the negative terminal and the interventionalelement being coupled to the positive terminal.

Clause 107. The system of any one of Clauses 85 to 106, wherein, whenthe interventional element and the distal portion of the catheter are inthe presence of an electrolytic medium and voltage is supplied to thefirst and second electrical terminals, current flows from theinterventional element to the electrode.

Clause 108. The system of any one of Clauses 85 to 107, wherein aproximal end of the interventional element is coupled to a distal end ofa core member, the core member extending proximally through thecatheter.

Clause 109. The system of Clause 108, wherein the core member comprisesan electrically conductive wire extending along its length.

Clause 110. The system of Clause 109, wherein the core member comprisesan insulative coating surrounding the wire along at least a portion ofits length.

Clause 111. The system of any one of Clauses 85 to 110, wherein theinterventional element is electrically conductive.

Clause 112. The system of any one of Clauses 85 to 111, wherein theinterventional element comprises a thrombectomy device.

Clause 113. The system of any one of Clauses 85 to 112, wherein theinterventional element comprises a stent retriever.

Clause 114. The system of any one of Clauses 85 to 113, wherein theinterventional element comprises a removal device.

Clause 115. The system of any one of Clauses 85 to 114, wherein theinterventional element comprises a catheter.

Clause 116. The system of any one of Clauses 85 to 115, wherein aportion of the interventional element is coated with a conductivematerial.

Clause 117. The system of Clause 116, wherein the conductive materialcomprises gold.

Clause 118. The system of any one of Clauses 85 to 117, wherein aportion of the interventional element is coated with a non-conductivematerial.

Clause 119. The system of Clause 118, wherein the non-conductivematerial comprises parylene.

Clause 120. A medical device delivery system, comprising:

-   -   a medical device coupled to a distal end of an elongate shaft,        the shaft configured to be electrically coupled to a first        terminal of a power supply; and    -   an elongate tubular member configured to receive the shaft        therethrough, the tubular member having an electrode disposed at        a distal portion thereof and a conductive lead electrically        coupled to the electrode, the conductive lead extending along a        length of the tubular member and configured to be electrically        coupled to a second terminal of the power supply.

Clause 121. The system of Clause 120, wherein the shaft and theconductive lead are configured to be coupled to first and secondterminals, respectively, of an extracorporeal power supply.

Clause 122. The system of any one of Clauses 120 to 121, wherein theshaft comprises a conductive element in electrical communication withthe medical device

Clause 123. The system of any one of Clauses 120 to 122, wherein themedical device is electrically conductive.

Clause 124. The system of any one of Clauses 120 to 123, wherein theconductive lead is disposed within a wall of the tubular member.

Clause 125. The system of any one of Clauses 120 to 123, wherein theconductive lead is disposed along an external surface of the tubularmember.

Clause 126. The system of any one of Clauses 120 to 125, wherein theelectrode comprises a conductive band extending at least partiallycircumferentially around the distal portion of the tubular member.

Clause 127. The system of Clause 126, wherein the conductive band isdisposed on an inner surface of the tubular member.

Clause 128. The system of Clause 126, wherein the conductive band isdisposed on an outer surface of the tubular member.

Clause 129. The system of any one of Clauses 120 to 128, wherein theelectrode comprises a stent engaged with an inner surface of the tubularmember.

Clause 130. The system of any one of Clauses 120 to 129, wherein thetubular member comprises an aspiration catheter.

Clause 131. The system of any one of Clauses 120 to 129, wherein thetubular member comprises a guide catheter.

Clause 132. The system of any one of Clauses 120 to 131, furthercomprising a suction source configured to supply negative pressurethrough the tubular member to aspirate a region adjacent to a distalportion of the tubular member.

Clause 133. The system of any one of Clauses 120 to 132, wherein thetubular member is an aspiration catheter having a proximal portionconfigured to be fluidically coupled to a suction source.

Clause 134. The system of any one of Clauses 120 to 133, furthercomprising a power supply having positive and negative terminals, theelectrode being coupled to the negative terminal and the shaft beingcoupled to the positive terminal.

Clause 135. The system of Clause 134, wherein, when the medical deviceand the distal portion of the tubular member are in the presence of anelectrolytic medium and voltage is supplied to the positive and negativeterminals, current flows from the medical device the electrode.

Clause 136. The system of any one of Clauses 120 to 135, wherein theshaft comprises an electrically conductive wire extending along itslength.

Clause 137. The system of Clause 136, wherein the shaft comprises aninsulative coating surrounding the wire along at least a portion of itslength.

Clause 138. The system of any one of Clauses 120 to 137, wherein themedical device comprises a thrombectomy device.

Clause 139. The system of any one of Clauses 120 to 138, wherein themedical device comprises a stent retriever.

Clause 140. The system of any one of Clauses 120 to 139, wherein themedical device comprises a removal device.

Clause 141. The system of any one of Clauses 120 to 140, wherein themedical device comprises a catheter.

Clause 142. The system of any one of Clauses 120 to 141, wherein aportion of the medical device is coated with a conductive material.

Clause 143. The system of Clause 142, wherein the conductive materialcomprises gold.

Clause 144. The system of any one of Clauses 120 to 143, wherein aportion of the medical device is coated with a non-conductive material.

Clause 145. The system of Clause 144, wherein the non-conductivematerial comprises parylene.

Clause 146. A method, comprising:

-   -   disposing a distal portion of a catheter adjacent to a treatment        site in the body, the catheter comprising an electrode disposed        in the distal portion and coupled to a first electrical terminal        of a power supply;    -   advancing an interventional element through the catheter to the        treatment site, the interventional element coupled to a second        electrical terminal of a power supply; and    -   supplying electric current to the second electrical terminal.

Clause 147. The method of Clause 146, further comprising ceasing thesupplying of electric current to the second electrical terminal after afirst time period.

Clause 148. The method of Clause 147, further comprising, after ceasingthe supplying of electric current, proximally retracting the core memberwith respect to the catheter.

Clause 149. The method of any one of Clauses 147 to 148, wherein thefirst time period is less than about 5 minutes.

Clause 150. The method of any one of Clauses 147 to 149, wherein thefirst time period is less than about 2 minutes.

Clause 151. The method of any one of Clauses 146 to 150, wherein theelectrode is coupled to the first electrical terminal via a conductivelead extending proximally along the catheter.

Clause 152. The method of Clause 151, wherein the conductive lead isdisposed within a wall of the catheter.

Clause 153. The method of Clause 151, wherein the conductive lead isdisposed along an external surface of the catheter.

Clause 154. The method of any one of Clauses 146 to 153, wherein theelectrode comprises a conductive band extending at least partiallycircumferentially around the distal portion of the catheter.

Clause 155. The method of Clause 154, wherein the conductive band isdisposed on an inner surface of the catheter.

Clause 156. The method of Clause 154, wherein the conductive band isdisposed on an outer surface of the catheter.

Clause 157. The method of any one of Clauses 146 to 156, wherein theelectrode comprises a stent engaged with an inner surface of thecatheter.

Clause 158. The method of any one of Clauses 146 to 157, furthercomprising supplying negative pressure through the catheter to aspiratea region adjacent to the treatment site.

Clause 159. The method of any one of Clauses 146 to 158, wherein thetreatment site in the body is proximate to or adjacent to a thrombus ina blood vessel.

Clause 160. The method of any one of Clauses 146 to 159, furthercomprising, after advancing the interventional element through thecatheter, expanding the interventional element adjacent to a thrombus ina blood vessel.

Clause 161. The method of any one of Clauses 146 to 160, wherein theinterventional element comprises a thrombectomy device.

Clause 162. The method of any one of Clauses 146 to 161, wherein theinterventional element comprises a stent retriever.

Clause 163. The method of any one of Clauses 146 to 162, wherein theinterventional element comprises a removal device.

Clause 164. The method of any one of Clauses 146 to 163, wherein theinterventional element is coupled to the second electrical terminal ofthe power supply via a conductive pushwire.

Clause 165. The method of any one of Clauses 146 to 164, furthercomprising:

-   -   arresting blood flow at the treatment site; and    -   after arresting the blood flow, supplying the electric current        to the second electrical terminal.

Clause 166. The method of Clause 165, further comprising:

-   -   ceasing the supplying of electric current to the second        electrical terminal after a first time period; and    -   after ceasing the supplying of electric current, restoring blood        flow at the treatment site.

Clause 167. The method of any one of Clauses 165 to 166, whereinarresting the blood flow comprises expanding a balloon of aballoon-guide catheter at a position proximal to the treatment site.

Clause 168. An aspiration device, comprising:

-   -   an aspiration catheter having a distal end configured to be        positioned adjacent to a thrombus in a blood vessel and a        proximal end configured to be fluidically coupled to a suction        source;    -   an electrode disposed at a distal portion of the aspiration        catheter; and    -   a conductive lead coupled to the electrode and extending along a        length of the catheter, the lead configured to be coupled to a        positive terminal of an extracorporeal power supply.

Clause 169. The device of Clause 168, wherein the electrode comprises aconductive band extending at least partially circumferentially aroundthe distal portion of the catheter.

Clause 170. The device of Clause 169, wherein the conductive band isdisposed on an inner surface of the catheter.

Clause 171. The device of any one of Clauses 168 to 170, wherein theconductive lead comprises a wire disposed within a wall of the catheter.

Clause 172. The device of any one of Clauses 168 to 170, wherein theconductive lead comprises a wire disposed around an external surface ofthe catheter.

Clause 173. The device of any one of Clauses 168 to 172, furthercomprising:

-   -   a second electrode; and    -   a second conductive lead coupled to the second electrode, the        second conductive lead configured to be coupled to a negative        terminal of the extracorporeal power supply.

Clause 174. The device of Clause 173, wherein the second electrodecomprises a conductive band disposed at the distal portion of thecatheter, and wherein the second conductive lead comprises a wiredisposed within a wall of the catheter.

Clause 175. The device of Clause 173, wherein the second electrodecomprises a conductive band disposed at the distal portion of thecatheter, and wherein the second conductive lead comprises a wiredisposed around an external surface of the catheter.

Clause 176. The device of Clause 173, wherein the second electrodecomprises a flow-arrest element coupled to the distal portion of thecatheter.

Clause 177. The device of Clause 173, wherein the second electrode isphysically separate from the catheter.

Clause 178. The device of Clause 177, wherein the second electrodecomprises a needle.

Clause 179. The device of Clause 177, wherein the second electrodecomprises a grounding pad.

Clause 180. The device of any one of Clauses 168 to 179, furthercomprising a suction source configured to supply negative pressurethrough the catheter to aspirate a region adjacent to the distal portionof the catheter.

Clause 181. The device of any one of Clauses 168 to 180, furthercomprising a power supply having positive and negative terminals, theconductive lead being coupled to the positive terminal and a returnelectrode being coupled to the negative terminal.

Clause 182. A method, comprising:

-   -   disposing a distal portion of a catheter adjacent to a treatment        site in the body, the catheter comprising a first electrode        disposed in the distal portion and coupled to a first electrical        terminal of a power supply;    -   supplying electric current to the first electrical terminal; and    -   supplying negative pressure through the catheter to aspirate a        region adjacent to the treatment site.

Clause 183. The method of Clause 182, further comprising disposing asecond electrode at a position spaced apart from the first electrode,the second electrode coupled to a second electrical terminal of thepower supply.

Clause 184. The method of Clause 183, wherein the first electricalterminal is positive, and wherein the second electrical terminal isnegative.

Clause 185. The method of any one of Clauses 183 to 184, wherein thesecond electrode comprises a needle.

Clause 186. The method of any one of Clauses 183 to 184, wherein thesecond electrode comprises a grounding pad.

Clause 187. The method of any one of Clauses 183 to 184, wherein thesecond electrode comprises a conductive element disposed in the distalportion of the catheter.

Clause 188. The method of any one of Clauses 182 to 187, furthercomprising supplying the electric current to the first electricalterminal while supplying the negative pressure through the catheter.

Clause 189. The method of any one of Clauses 182 to 188, furthercomprising ceasing the supplying of electric current to the firstelectrical terminal after a first time period.

Clause 190. The method of Clause 189, wherein the first time period isless than about 5 minutes.

Clause 191. The method of Clause 189, wherein the first time period isless than about 2 minutes.

Clause 192. The method of any one of Clauses 182 to 191, wherein thefirst electrode is coupled to the first electrical terminal via aconductive lead extending proximally along the catheter.

Clause 193. The method of Clause 192, wherein the conductive lead isdisposed within a wall of the catheter.

Clause 194. The method of Clause 192, wherein the conductive lead isdisposed along an external surface of the catheter.

Clause 195. The method of Clause 182 to 194, wherein the first electrodecomprises a conductive band extending at least partiallycircumferentially around the distal portion of the catheter.

Clause 196. The method of Clause 195, wherein the conductive band isdisposed on an inner surface of the catheter.

Clause 197. The method of Clause 195, wherein the conductive band isdisposed on an outer surface of the catheter.

Clause 198. The method of any one of Clauses 182 to 197, wherein thefirst electrode comprises a stent engaged with an inner surface of thecatheter.

Clause 199. The method of any one of Clauses 182 to 198, wherein thetreatment site in the body is proximate to or adjacent to a thrombus ina blood vessel.

Additional features and advantages of the present technology aredescribed below, and in part will be apparent from the description, ormay be learned by practice of the present technology. The advantages ofthe present technology will be realized and attained by the structureparticularly pointed out in the written description and claims hereof aswell as the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present technology can be better understood withreference to the following drawings. The components in the drawings arenot necessarily to scale. Instead, emphasis is placed on illustratingclearly the principles of the present disclosure.

FIG. 1A shows a perspective view of an electrically enhanced treatmentsystem for retrieving material from a body lumen, in accordance with oneor more embodiments of the present technology.

FIGS. 1B and 1C are schematic views of different embodiments of thecurrent generator illustrated in FIG. 1A.

FIG. 2A is a side schematic view of a portion of the treatment system ofFIG. 1A.

FIG. 2B is a side schematic cross-sectional view of a portion of thetreatment system shown in FIG. 2A.

FIG. 3A illustrates an interventional element with one or more coatingsin accordance with embodiments of the present technology.

FIGS. 3B and 3C are charts showing clot detachment forces forinterventional elements coated with a conductive material and fornon-coated interventional elements, in accordance with the presenttechnology.

FIGS. 4A-4G illustrate a method of removing clot material from a bloodvessel lumen using an electrically enhanced treatment system.

FIG. 5 is a chart showing clot detachment forces for differentinterventional element embodiments under different environments.

FIGS. 6A-6B illustrate a method of removing clot material from a bloodvessel lumen using electrically enhanced aspiration.

FIGS. 7A-7E illustrate sample waveforms for electrically enhancedremoval of material from vessel lumens in accordance with one or moreembodiments of the present disclosure.

DETAILED DESCRIPTION

The present technology provides devices, systems, and methods forremoving clot material from a blood vessel lumen. Although many of theembodiments are described below with respect to devices, systems, andmethods for treating a cerebral or intracranial embolism, otherapplications and other embodiments in addition to those described hereinare within the scope of the technology. For example, the treatmentsystems and methods of the present technology may be used to removeemboli from body lumens other than blood vessels (e.g., the digestivetract, etc.) and/or may be used to remove emboli from blood vesselsoutside of the brain (e.g., pulmonary, abdominal, cervical, or thoracicblood vessels, or peripheral blood vessels including those within thelegs or arms, etc.). In addition, the treatment systems and methods ofthe present technology may be used to remove luminal obstructions otherthan clot material (e.g., plaque, resected tissue, foreign material,etc.).

I. Select Embodiments of Electrically Enhanced Treatment Systems

FIG. 1A illustrates a view of an electrically enhanced treatment system10 according to one or more embodiments of the present technology. Asshown in FIG. 1A, the treatment system 10 can include a currentgenerator 20 and a treatment device 40 having a proximal portion 40 aconfigured to be coupled to the current generator 20 and a distalportion 40 b configured to be intravascularly positioned within a bloodvessel (such as an intracranial blood vessel) at a treatment site at orproximate a thrombus. The treatment device 40 includes an interventionalelement 100 at the distal portion 10 b, a handle 16 at the proximalportion 10 a, and a plurality of elongated shafts or members extendingtherebetween. For example, in some embodiments, such as that shown inFIG. 1A, the treatment device 40 includes a first catheter 14 (such as aballoon guide catheter), a second catheter 13 (such as a distal accesscatheter or aspiration catheter) configured to be slidably disposedwithin a lumen of the first catheter 14, a third catheter 12 (such as amicrocatheter) configured to be slidably disposed within a lumen of thesecond catheter 13, and a core member 11 configured to be slidablydisposed within a lumen of the third catheter 12. In some embodiments,the treatment device 40 does not include the second catheter 13. Thefirst catheter 14 can be coupled to the handle 16, which providesproximal access to the core member 11 that engages the interventionalelement 100 at a distal end thereof. The current generator 20 may becoupled to a proximal portion of one or more of the core member 11, thethird catheter 12, the second catheter 13, and/or the first catheter 14to provide an electrically charged environment at the distal portion 40b of the treatment device 40, as described in more detail below.

In some embodiments, the treatment system 10 includes a suction source25 (e.g., a syringe, a pump, etc.) configured to be fluidly coupled(e.g., via a connector 23) to a proximal portion of one or more of thefirst catheter 14, the second catheter 13, and/or the third catheter 12to apply negative pressure therethrough. In some embodiments, thetreatment system 10 includes a fluid source 27 (e.g., a fluid reservoir,a syringe, pump, etc.) configured to be fluidly coupled (e.g., via theconnector 23) to a proximal portion of one or more of the first catheter14, the second catheter 13, and/or the third catheter 12 to supply fluid(e.g., saline, contrast agents, a drug such as a thrombolytic agent,etc.) to the treatment site.

According to some embodiments, the current generator 20 can include anelectrical generator configured to output medically useful electriccurrent. FIGS. 1B and 1C are schematic views of different embodiments ofthe current generator 20. With reference to FIG. 1B, the currentgenerator 20 can include a power source 22, a first terminal 24, asecond terminal 26, and a controller 28. The controller 28 includes aprocessor 30 coupled to a memory 32 that stores instructions (e.g., inthe form of software, code or program instructions executable by theprocessor or controller) for causing the power source 22 to deliverelectric current according to certain parameters provided by thesoftware, code, etc. The power source 22 of the current generator 20 mayinclude a direct current power supply, an alternating current powersupply, and/or a power supply switchable between a direct current and analternating current. The current generator 20 can include a suitablecontroller that can be used to control various parameters of the energyoutput by the power source or generator, such as intensity, amplitude,duration, frequency, duty cycle, and polarity. For example, the currentgenerator 20 can provide a voltage of about 2 volts to about 28 voltsand a current of about 0.5 mA to about 20 mA.

FIG. 1C illustrates another embodiment of the current generator 20, inwhich the controller 28 of FIG. 1B is replaced with drive circuitry 34.In this embodiment, the current generator 20 can include hardwiredcircuit elements to provide the desired waveform delivery rather than asoftware-based generator of FIG. 1B. The drive circuitry 34 can include,for example, analog circuit elements (e.g., resistors, diodes, switches,etc.) that are configured to cause the power source 22 to deliverelectric current via the first and second terminals 24, 26 according tothe desired parameters. For example, the drive circuitry 34 can beconfigured to cause the power source 22 to deliver periodic waveformsvia the first and second terminals 24, 26.

As noted above, the current generator 20 may be coupled to a proximalportion of the core member 11, and/or a proximal portion of the thirdcatheter 12, the second catheter 13, and/or first catheter 14 to providean electric current to the interventional element 100. For example, insome embodiments, both terminals of the current generator 20 are coupledto the core member 11 such that the core member 11 functions as both adelivery electrode or conductive path (i.e., transmitting current fromthe current generator 20 to the treatment site) and a return electrodeor conductive path (i.e., transmitting current from the treatment siteto the current generator 20) (described in greater detail below withreference to FIG. 2B). In other embodiments, the return electrode can beseparate from the core member 11. For example, the return electrode canbe carried by one or more of the third catheter 12, the second catheter13, and/or first catheter 14. In some embodiments, the return electrodecan be provided via one or more external electrodes 29 (FIG. 1A), suchas a needle puncturing the patient or a grounding pad applied to thepatient's skin. In some embodiments, the return electrode can be aninsulated guide wire having an exposed, electrically conductive portionat its distal end.

FIG. 2A is a side schematic view of a portion of the treatment device 40shown in FIG. 1A. The system 10 can include can include multiple (e.g.,two or more), distinct conductive paths or channels for passingelectrical current along the system 10. The interventional element 100can serve as one electrode (e.g., the delivery electrode) in electricalcommunication with a conductive path integrated into the core member 11.Another of the conductive paths of the system 10 can be in electricalcommunication with another electrode (e.g., a return electrode). Thevarious embodiments of the core member 11 can be sized for insertioninto a bodily lumen, such as a blood vessel, and can be configured topush and pull a device such as the interventional element 100 along thebodily lumen.

As noted above, the interventional element 100 can serve as the deliveryelectrode and be electrically coupled to a positive terminal of thecurrent generator 20 (FIG. 1A). As shown in FIG. 2B, in someembodiments, the core member 11 can include an elongate conductive shaft211 (e.g., a pushwire) extending along the length of the core member 11.The shaft can be in electrical communication with the current generator20 (FIG. 1A) at its proximal end and the interventional element 100 atits distal end. The shaft can be insulated along at least a portion ofits length, with exposed portions permitting electrical communicationwith the current generator 20 and the interventional element 100.

The return electrode(s) can assume a variety of configurations indifferent embodiments. For example, in some embodiments, the returnelectrode is an external electrode 29 (FIG. 1A), such as a needle orgrounding pad that is applied to a patient's skin. The needle orgrounding pad can be coupled via one or more leads to the currentgenerator 20 to complete the electrical circuit. In some embodiments,the return electrode is carried by a surrounding catheter (e.g., thirdcatheter 12, second catheter 13, and/or first catheter 14), as describedin more detail below.

According to some embodiments, for example as shown in FIG. 2A, thecatheters 12, 13, and 14 can each be formed as a generally tubularmember extending along and about a central axis and terminating in arespective distal end 201, 202, and 203. According to some embodiments,the third catheter 12 is generally constructed to track over aconventional guidewire in the cervical anatomy and into the cerebralvessels associated with the brain and may also be chosen according toseveral standard designs that are generally available. Accordingly, thethird catheter 12 can have a length that is at least 125 cm long, andmore particularly may be between about 125 cm and about 175 cm long.Other designs and dimensions are contemplated.

The second catheter 13 can be sized and configured to be slidablyreceive the third catheter 12 therethrough. As noted above, the secondcatheter 13 can be coupled at a proximal portion to a suction source 25(FIG. 1A) such as a pump or syringe in order to supply negative pressureto a treatment site. The first catheter 14 can be sized and configuredto slidably receive both the second catheter 13 and the third catheter12 therethrough. In some embodiments, the first catheter 14 is aballoon-guide catheter having an inflatable balloon or other expandablemember that can be used to anchor the first catheter 14 with respect toa surrounding vessel. As described in more detail below with respect toFIGS. 4A-4G, in operation the first catheter 14 can first be advancedthrough a vessel and then a balloon can be expanded to anchor the firstcatheter 14 in place and/or arrest blood flow from areas proximal of theballoon. Next, the second catheter 13 can be advanced through the firstcatheter 14 until its distal end 202 extends distally beyond the distalend 203 of the first catheter 14. The second catheter 13 can bepositioned such that its distal end 202 is adjacent a treatment site(e.g., a site of a blood clot within the vessel). The third catheter 12may then be advanced through the second catheter 13 until its distal end201 extends distally beyond the distal end 202 of the second catheter13. The interventional element 100 may then be advanced through thethird catheter 12 for delivery to the treatment site.

According to some embodiments, the bodies of the catheters 12, 13, and14 can be made from various thermoplastics, e.g.,polytetrafluoroethylene (PTFE or TEFLON®), fluorinated ethylenepropylene (FEP), high-density polyethylene (HDPE), polyether etherketone (PEEK), etc., which can optionally be lined on the inner surfaceof the catheters or an adjacent surface with a hydrophilic material suchas polyvinylpyrrolidone (PVP) or some other plastic coating.Additionally, either surface can be coated with various combinations ofdifferent materials, depending upon the desired results.

According to some embodiments, an electrode 204 is provided at a distalend region of the third catheter 12. The electrode 204 can form anannular ring that extends entirely circumferentially about the centralaxis of the third catheter 12. Alternatively or in combination, theelectrode 204 can extend less than entirely circumferentially around thethird catheter 12. For example, the electrode 204 may be entirelydisposed on one radial side of the central axis. By further example, theelectrode 204 may provide a plurality of discrete, noncontiguouselectrode sections about the central axis. Such sections of theelectrode 204 can be in electrical communication with a commonconductive path so as to function collectively as a single electrode, orwith multiple separate such paths to allow the sections to functionindependently if desired. The electrode 201 can be a band, a wire, or acoil embedded in the wall of the third catheter 12. According to someembodiments, the electrode 204 can be longitudinally separated from thedistal end 201 of the third catheter 12 by a non-conductive portion ofthe third catheter 12. Alternatively, a distal portion of the electrode204 can extend to the distal end 201 of the third catheter 12, such thatthe electrode 204 forms a portion of the distal end 201. According tosome embodiments, an inner surface of the electrode 204 can be flushwith an inner surface of the third catheter 12. Alternatively or incombination, the inner surface of the electrode 204 can extend moreradially inwardly relative to the inner surface of the third catheter 12(e.g., providing a “step”). Alternatively or in combination, the innersurface of the electrode 204 can extend less radially inwardly relativeto the inner surface of the third catheter 12 (e.g., be recessed intothe body). According to some embodiments, the electrode 201 can besurrounded radially by an outer section of the third catheter 12 toprovide insulation from an external environment. In some embodiments, anouter surface of the electrode 204 can be flush with an outer surface ofthe third catheter 12 and can provide an exposed, radially outwardlyfacing electrode surface. In such instances, a radially inner section ofthe third catheter 12 can provide insulation from the environment withinthe lumen of the third catheter 12.

The electrode 204 can include one or more rings, one or more coils orother suitable conductive structures, and can each form at least onesurface (e.g., an inner surface or an outer surface) that is exposed andconfigured for electrical activity or conduction. The electrode 204 canhave a fixed inner diameter or size, or a radially expandable innerdiameter or size. In some embodiments, the electrode 204 is a “painted”electrode. The electrode can include platinum, platinum alloys (e.g.,92% platinum and 8% tungsten, 90% platinum and 10% iridium), gold,cobalt-chromium, stainless steel (e.g., 304 or 316), nitinol, andcombinations thereof, or any suitable conductive materials, metals oralloys.

In some embodiments, the electrode 204 can be a separate expandablemember coupled to an outer surface of the third catheter 12, for examplea braid, stent, or other conductive element coupled to an outer surfaceof the distal portion of the third catheter 12. In some embodiments, theelectrode can be part of a flow-arrest element such as an expandablebraid coupled to an occlusion balloon.

According to some embodiments, the electrode 204 can be electricallyconnected to the current generator 20 via a conductive lead 205. Theconductive lead 205 can extend proximally along or within the wall ofthe third catheter 12 to or beyond the proximal end of the thirdcatheter 12. The conductive lead 205 can include more than oneconductive path extending within the walls of the third catheter 12.According to some embodiments, the conductive lead 205 can form ahelical coil along or within at least a portion of the third catheter12. Alternatively or in combination, the conductive lead 205 can form abraided, woven, or lattice structure along or within at least a portionof the third catheter 12. In some embodiments, the conductive lead 205can be a conductive element (e.g., a wire, coil, etc.) wrapped around anexternal surface of the third catheter 12. In such instances, theconductive lead 205 can be coated with an insulative material along atleast a portion of its length. The insulative material can be, forexample, Parylene, PTFE, or other suitable insulative material.

In some embodiments, the second catheter 13 and/or the first catheter 14can be similarly equipped with corresponding electrodes instead of or inaddition to the third catheter 12 or the core member 11. For example,the second catheter 13 may include an electrode 206 disposed at a distalend region of the second catheter 13. The electrode 206 can beelectrically connected to the current generator 20 (FIG. 1A) via aconductive lead 207 which extends proximally along the second catheter13. The configuration of the electrode 206 and the correspondingconductive lead 207 can be similar to any of the variations describedabove with respect to the electrode 204 and the conductive lead 205 ofthe third catheter 12.

In some embodiments, the first catheter 14 includes an electrode 208disposed at a distal end region of the first catheter 14. The electrode208 can be electrically connected to the current generator 20 (FIG. 1A)via a conductive lead 209 which extends proximally along the firstcatheter 14. The configuration of the electrode 208 and thecorresponding conductive lead 209 can be similar to any of thevariations described above with respect to the electrode 204 and theconductive lead 205 of the third catheter 12.

In various embodiments, the system can include any combination of theelectrodes 204, 206, and 208 described above. For example, the systemmay include the electrode 204 and the corresponding conductive lead 205of the third catheter 12, while the second catheter 13 and the firstcatheter 14 may be provided with no electrodes or conductive leadstherein. In other embodiments, the system may only include the electrode206 of the second catheter 13, while the third catheter 12 and the firstcatheter 14 may be provided with no electrodes or conductive leadstherein. In still other embodiments, the system may include only theelectrode 208 of the first catheter 14, while the third catheter 12 andthe second catheter 13 are provided with no electrodes or correspondingconductive leads therein. In some embodiments, any two of the catheters12, 13, or 14 can be provided with electrodes and corresponding leads,while the remaining catheter may have no electrode or conductive leadtherein.

In the configuration illustrated in FIG. 2A, one or more of electrodes204, 206, or 208 can be coupled to a negative terminal of the currentgenerator 20, while the interventional element 100 can be coupled to thepositive terminal of the current generator 20 via the core member 11. Asa result, when voltage is applied at the terminals and theinterventional element 100 placed in the presence of blood (or any otherelectrolytic medium), current flows from the interventional element 100,through the blood or medium, and to the return electrode. The returnelectrode may a conductive element carried by one or more of thecatheters 12, 13, or 14 as described above, or the core member 11, or insome embodiments the return electrode can be an external electrode 29(FIG. 1A) such as needle or grounding pad.

In some embodiments, one or more catheters carrying an electrode can beused without an electrically coupled interventional element 100. Invarious embodiments, the interventional element 100 may be omittedaltogether (as in FIGS. 6A-6B described below), or the interventionalelement 100 may be included but may not be electrically coupled to thecurrent generator 20. In such cases, a catheter-based electrode (e.g.,the electrode 204 carried by the third catheter 12, the electrode 206carried by the second catheter 13, or the electrode 208 carried by thefirst catheter 14) can function as the delivery electrode, and aseparate return electrode can be provided either in the form of anothercatheter-based electrode (either carried by the same catheter or carriedby another catheter) or as an external electrode (e.g., a needle orgrounding pad). In instances in which a single catheter carries twoelectrodes, one electrode may be provided on an exterior surface of thecatheter while the other electrode may be provided on an inner surfaceof the catheter. For example, the second catheter 13 may include adelivery electrode in the form of a conductive band disposed on an innersurface of the catheter 13, in addition to a return electrode in theform of a conductive band disposed on an outer surface of the catheter13.

As described in more detail in FIG. 2B, in some embodiments the returnelectrode can be integrated into the core member 11 of the treatmentsystem 10, such that the core member 11 carries two separate conductivepaths along its length. FIG. 2B is a side schematic cross-sectional viewof a portion of the treatment system shown in FIG. 2A, in accordancewith some embodiments. As shown in FIG. 2B, the core member 11 includesan elongate conductive shaft 211 and an elongate tubular member 212having a lumen through which the shaft 211 extends. The shaft 211 has adistal portion 210, and the tubular member 212 has a distal portion 218.Both the shaft 211 and the tubular member 212 are electricallyconductive along their respective lengths. In some embodiments, thepositions of the shaft 211 and the tubular member 212 are fixed relativeto one another. For example, in some embodiments the shaft 211 is notslidable or rotatable with respect to the tubular member 212 such thatthe core member 11 can be pushed or pulled without relative movementbetween the shaft 211 and the tubular member 212 and/or other individualcomponents of the core member 11.

In some embodiments, the shaft 211 can be a solid pushwire, for examplea wire made of Nitinol, stainless steel, or other metal or alloy. Theshaft 211 may be thinner than would otherwise be required due to theadditional structural column strength provided by the surroundingtubular member 212. The tubular member 212 can be a hollow wire,hypotube, braid, coil, or other suitable member(s), or a combination ofwire(s), tube(s), braid(s), coil(s), etc. In some embodiments, thetubular member 212 can be a laser-cut hypotube having a spiral cutpattern (or other pattern of cut voids) formed in its sidewall along atleast a portion of its length. The tubular member 212 can be made ofstainless steel (e.g., 304 SS), Nitinol, and/or other alloy. In at leastsome embodiments, the tubular member 212 can have a laser cut pattern toachieve the desired mechanical characteristics (e.g., column strength,flexibility, kink-resistance, etc.).

The core member 11 can also include an adhesive or a mechanical couplersuch as a crimped band or marker band 220 disposed at the distal end ofthe core member 11, and the marker band 220 can optionally couple thedistal end of the core member 11 to the interventional element 100. Themarker band 220 can be radiopaque, for example including platinum orother radiopaque material, thereby enabling visualization of theproximal end of the interventional element 100 under fluoroscopy. Insome embodiments, additional radiopaque markers can be disposed atvarious locations along the treatment system 10, for example along theshaft 211, the tubular member 212, or the interventional element 100(e.g., at the distal end, or along the length, of the interventionalelement 100).

In at least some embodiments, the core member 11 also includes a firstinsulating layer or material 222 extending between the shaft 211 and thesurrounding tubular member 212. The first insulating material 222 canbe, for example, PTFE (polytetrafluoroethylene or TEFLON™) or any othersuitable electrically insulating coating (e.g., polyimide, oxide,ETFE-based coatings, or any suitable dielectric polymer). In someembodiments, the first insulating material 222 extends alongsubstantially the entire length of the shaft 211. In some embodiments,the first insulating material 222 separates and electrically insulatesthe shaft 211 and the tubular member 212 along the entire length of thetubular member 212. In some embodiments, the first insulating material222 does not cover the proximal-most portion of the shaft 211, providingan exposed region of the shaft to which the current generator 20 (FIG.1A) can be electrically coupled. In some embodiments, for example, thefirst insulating material 222 terminates proximally at the proximalterminus of the shaft, and the current generator 20 (FIG. 1A) canelectrically couple to the shaft 211 at its proximal terminus, forexample using a coaxial connector.

The core member 11 can additionally include a second insulating layer ormaterial 224 surrounding the tubular member 212 along at least a portionof its length. The second insulating layer 224 can be, for example, PTFEor any other suitable electrically insulative coating (e.g., polyimide,oxide, ETFE based coatings or any suitable dielectric polymer). In someembodiments, the distal portion 218 of the tubular member 212 is notcovered by the second insulating layer 224, leaving an exposedconductive surface at the distal portion 218. In some embodiments, thelength of the exposed distal portion 218 of the tubular member 212 canbe at least (or equal to) 1, 2, 3, 4, 5, 6, or more inches. In someembodiments, the length of the exposed distal portion 218 of the tubularmember 212 can be between at least 1 and 10 inches, or between 2 inchesand 8 inches, or between 3 and 7 inches, or between 4 and 6 inches, orabout 5 inches. This exposed portion of the distal portion 218 of thetubular member 212 provides a return path for current supplied to thedelivery electrode (e.g. the entirety or a portion of the interventionalelement 100), as described in more detail below. In some embodiments,the second insulating material 224 does not cover the proximal-mostportion of the tubular member 212, providing an exposed region of thetubular member 212 to which the current generator 20 (FIG. 1A) can beelectrically coupled. In some embodiments, the second insulatingmaterial 224 proximally terminates at the proximal terminus of thetubular member 212, and the current generator 20 can electrically coupleto the tubular member 212 at its proximal terminus, for example using acoaxial connector.

The core member 11 can also include a retraction marker in the proximalportion of the tubular member 212. The retraction marker can be avisible indicator to guide a clinician when proximally retracting anoverlying catheter with respect to the core member 11. For example, theretraction marker can be positioned such that when a proximal end of theoverlying catheter is retracted to be positioned at or near theretraction marker, the distal portion 218 of the tubular member 212 ispositioned distally beyond a distal end of the catheter. In thisposition, the exposed distal portion 218 of the tubular member 212 isexposed to the surrounding environment (e.g., blood, tissue, etc.), andcan serve as a return electrode for the core member 11.

The proximal end of the shaft 211 can be electrically coupled to thepositive terminal of the current generator 20, and the proximal end ofthe tubular member 212 can be electrically coupled to the negativeterminal of the current generator 20. During operation, the treatmentsystem 10 provides an electrical circuit in which current flows from thepositive terminal of the current generator 20, distally through theshaft 211, the interventional element 100, and the surrounding media(e.g., blood, tissue, thrombus, etc.) before returning back to theexposed distal portion 218 of the tubular member, proximally through thetubular member 212, and back to the negative terminal of the currentgenerator 20 (FIG. 1A).

As noted above, the current generator 20 (FIG. 1A) can include a powersource and either a processor coupled to a memory that storesinstructions for causing the power source to deliver electric currentaccording to certain parameters, or hardwired circuit elementsconfigured to deliver electric current according to the desiredparameters. The current generator 20 may be integrated into the coremember 11 or may be removably coupled to the core member 11, for examplevia clips, wires, plugs or other suitable connectors. Particularparameters of the energy provided by the current generator 20 aredescribed in more detail below with respect to FIGS. 7A-7E.

In certain embodiments, the polarities of the current generator 20 canbe switched, so that the negative terminal is electrically coupled tothe shaft 211 and the positive terminal is electrically coupled to thetubular member 212. This can be advantageous when, for example,attempting to attract predominantly positively charged material to theinterventional element 100, or when attempting to break up a clot ratherthan grasp it with an interventional element. In some embodimentsalternating current (AC) signals may be used rather than DC. In certaininstances, AC signals may advantageously help break apart a thrombus orother material.

II. Select Embodiments of Interventional Elements for Use with theTreatment Systems Disclosed Herein

Referring still to FIGS. 2A and 2B, in some embodiments theinterventional element 100 can be a metallic or electrically conductivethrombectomy device. The interventional element 100 can have alow-profile, constrained or compressed configuration (not shown) forintravascular delivery to the treatment site within the third catheter12, and an expanded configuration for securing and/or engaging clotmaterial and/or for restoring blood flow at the treatment site. Theinterventional element 100 has a proximal portion 100 a that may becoupled to the core member 11 and a distal portion 100 b. Theinterventional element 100 further includes an open cell framework orbody 226 and a coupling region 228 extending proximally from the body226. In some embodiments, the body 226 of the interventional element 100can be generally tubular (e.g., cylindrical), and the proximal portion100 a of the interventional element 100 can taper proximally to thecoupling region 228.

In various embodiments, the interventional element 100 can take anynumber of forms, for example a removal device, a thrombectomy device, orother suitable medical device. For example, in some embodiments theinterventional element 100 may be a stent and/or stent retriever, suchas Medtronic's Solitaire™ Revascularization Device, StrykerNeurovascular's Trevo® ProVue™ Stentriever, or other suitable devices.In some embodiments, the interventional element 100 may be a coiledwire, a weave, and/or a braid formed of a plurality of braidedfilaments. Examples of suitable interventional elements 100 include anyof those disclosed in U.S. Pat. No. 7,300,458, filed Nov. 5, 2007, U.S.Pat. No. 8,940,003, filed Nov. 22, 2010, U.S. Pat. No. 9,039,749, filedOct. 1, 2010, and U.S. Pat. No. 8,066,757, filed Dec. 28, 2010, each ofwhich is incorporated by reference herein in its entirety.

In some embodiments, the interventional element 100 is a mesh structure(e.g., a braid, a stent, etc.) formed of a superelastic material (e.g.,Nitinol) or other resilient or self-expanding material configured toself-expand when released from the third catheter 12. The mesh structuremay include a plurality of struts 101 and open spaces 103 between thestruts 101. In some embodiments, the struts 101 and spaces 103 may besituated along the longitudinal direction of the interventional element100, the radial direction, or both.

As depicted in FIG. 2A, the interventional element 100 may comprise aworking length WL portion and a non-working length NWL portion. Theportion of the interventional element 100 in the working length WL maybe configured to interlock, capture, and/or engage a thrombus. Theportion of the interventional element 100 in the non-working length NWLmay contact thrombotic material in use, but is configured to perform afunction that renders it ineffective or less effective than the workinglength WL portion for interlocking, capturing, and/or engaging with athrombus. In some embodiments, such as that shown in FIG. 2A, a distalterminus of the working length WL portion is proximal of the distalterminus of the interventional element 100 (i.e., the working length WLportion is spaced apart from the distal terminus of the interventionalelement 100), and the non-working length NWL portion is disposed betweenthe working length WL and the band 220 and/or the distal end of the coremember 11.

In some embodiments, the non-working length NWL portion of theinterventional element 100 can be coated with a non-conductive orinsulative material (e.g., Parylene, PTFE, or other suitablenon-conductive coating) such that the coated region is not in electricalcontact with the surrounding media (e.g., blood). As a result, thecurrent carried by the core member 11 to the interventional element 100is only exposed to the surrounding media along the working length WLportion of the interventional element 100. This can advantageouslyconcentrate the electrically enhanced attachment effect along theworking length WL of the interventional element 100, where it is mostuseful, and thereby combine both the mechanical interlocking provided bythe working length WL and the electrical enhancement provided by thedelivered electrical signal. In some embodiments, a distal region of theinterventional element 100 (e.g. distal of the working length WL) maylikewise be coated with a non-conductive material (e.g., Parylene, PTFE,or other suitable non-conductive coating), leaving only a centralportion or the working length WL of the interventional element 100having an exposed conductive surface.

In some embodiments, the interventional element 100 may include aconductive material positioned on some or all of its outer surface. Theconductive material, for example, can be gold and/or another suitableconductor that has a conductivity greater than (or a resistivity lessthan) that of the material comprising the interventional element 100.The conductive material may be applied to the interventional element 100via electrochemical deposition, sputtering, vapor deposition,dip-coating, and/or other suitable means. FIG. 3A, for example, is across-sectional view of a strut 101 of the interventional element 100having a conductive material 301 disposed thereon. Although the strut101 shown in FIG. 3A has a generally square or rectangularcross-sectional shape, in some embodiments the interventional element100 includes one or more struts or filaments having othercross-sectional shapes (e.g., circle, oval, etc.).

As shown in FIG. 3A, the strut 101 has a surface comprised of an outerportion 101 a facing away from a lumen of the interventional element100, an inner portion 101 c facing toward the lumen, and side portions101 b and 101 d extending between the outer and inner portions 101 a,101 c. In some embodiments, such as that shown in FIG. 3A, theconductive material 301 may be disposed only at the outer portion 101 aof the strut 101 and the inner and side portions 101 b-d may be exposedor otherwise not in contact with or covered by the conductive material301. In some embodiments, the conductive material 301 may be disposedonly on the inner portion 101 c of the surface, only on one of the sideportions 101 b, 101 d, or on any combination of the surface portions 101a-d.

In some aspects of the present technology, the conductive material 301is disposed only on the working length WL portion of the interventionalelement 100 such that the proximal and distal portions 100 a, 100 b ofthe interventional element 100 are exposed. Because the conductivematerial 301 has a much lower resistance than the underlying materialcomprising the interventional element 100, current delivered to theinterventional element 100 concentrates along the working length WLportion. In several of such embodiments, the conductive material 301 maybe disposed only on the outer portion 101 a of the strut surface alongthe working length WL portion. In other embodiments, the conductivematerial 301 may be disposed on all or a portion of the strut surfacealong all or a portion of the length of the interventional element 100.

In some embodiments, a first portion of the interventional element 100is covered by the conductive material 301 and a second portion of theinterventional element 100 is covered by an insulative or dielectricmaterial (e.g., Parylene). For example, in some embodiments the outerportion 101 a of the strut surface is covered by a conductive materialwhile an inner portion 101 c of the strut surface is covered by aninsulative material. In some embodiments, the working length WL portionof the interventional element 100 may be covered by a conductivematerial while the non-working length NWL portion is covered by aninsulative material. In some embodiments, the conductive material 301may be disposed on all or a portion of the strut surface along all or aportion of the length of the interventional element 100, and theinsulative material may be disposed on those portions of the strutsurface and/or working length not covered by the conductive material.

FIGS. 3B and 3C demonstrate the improved adhesion strength between clotmaterial and the interventional element 100 as a result of theconductive material. The charts of FIGS. 3B and 3C, for example, showdetachment forces for gold-coated and non-coated (“SS”) interventionalelements 100 that received electric current while exposed to sheep's orpig's blood, respectively. For these experiments, a blood clot wasmanufactured by mixing fibrinogen, blood, thrombin and calcium chloride.A representative interventional element was immersed or deployed incontact with the blood clot to mimic clinical deployment and positivecharge was applied to it for a specified duration. The whole assemblywas immersed in blood and flow was applied at 150 mL/min. Thecomposition of the manufactured blood clot and the parameters of theapplied energy (e.g., duration, amplitude, etc.) were generally the samefor all samples in both experiments. The assembly (blood clot andinterventional element) was then removed from the experimental setup andthe blood clot was detached from the interventional element using alap-shear test with an Instron. The detachment force was measured and isreported in the charts. In both charts, the average detachment force forthe gold-coated samples is at least two times the average detachmentforce for the non-coated samples.

III. Select Methods of Use

FIGS. 4A-4G illustrate a method of removing clot material CM from thelumen of a blood vessel V using the treatment system 10 of the presenttechnology. As shown in FIG. 4A, the first catheter 14 can be advancedthrough the vasculature and positioned within the blood vessel such thata distal portion of the first catheter 14 is proximal of the clotmaterial CM. As shown in FIG. 4B, the second catheter 13 may be advancedthrough the first catheter 14 until a distal portion of the secondcatheter 13 is at or proximal to the clot material CM. Next, the thirdcatheter 12 may be advanced through the second catheter 13 so that adistal portion of the third catheter 12 is positioned at or near theclot material CM. In some embodiments, the third catheter 12 may bepositioned such that a distal terminus of the third catheter 12 isdistal of the clot material CM. The interventional element 100 may thenbe advanced through the third catheter 12 in a low-profile configurationuntil a distal terminus of the interventional element 100 is at oradjacent the distal terminus of the third catheter 12.

As shown in FIG. 4C, the third catheter 12 may be withdrawn proximallyrelative to the interventional element 100 to release the interventionalelement 100, thereby allowing the interventional element 100 toself-expand within the clot material CM. As the interventional element100 expands, the interventional element 100 engages and/or secures thesurrounding clot material CM, and in some embodiments may restore orimprove blood flow through the clot material CM by pushing open a bloodflow path therethrough. In some embodiments, the interventional element100 may be expanded distal of the clot material CM such that no portionof the interventional element 100 is engaging the clot material CM whilethe interventional element 100 is in the process of expanding toward thevessel wall. In some embodiments, the interventional element 100 isconfigured to expand into contact with the wall of the vessel V, or theinterventional element 100 may expand to a diameter that is less thanthat of the blood vessel lumen such that the interventional element 100does not engage the entire circumference of the blood vessel wall.

Once the interventional element 100 has been expanded into engagementwith the clot material CM, the interventional element 100 may grip theclot material CM by virtue of its ability to mechanically interlock withthe clot material CM. The current generator 20, which is electricallycoupled to the proximal end of the core member 11, can deliver a currentto the interventional element 100 before or after the interventionalelement 100 has been released from the third catheter 12 into the bloodvessel and/or expanded into the clot material CM. The interventionalelement 100 can be left in place or manipulated within the vessel V fora desired time period while the electrical signal is being delivered.Positive current delivered to the interventional element 100 can attractnegatively charged constituents of the clot material CM, therebyenhancing the grip of the interventional element 100 on the clotmaterial CM. This allows the interventional element 100 to be used toretrieve the clot material CM with reduced risk of losing grip on thethrombus or a piece thereof, which can migrate downstream and causeadditional vessel blockages in areas of the brain that are moredifficult to reach.

In some methods of the present technology, a guidewire (not shown) maybe advanced to the treatment site and pushed through the clot materialCM until a distal portion of the guidewire is distal of the clotmaterial CM. The guidewire may be advanced through one or more of thecatheters 12-14 and/or one or more of the catheters 12-14 may beadvanced over the guidewire. The guidewire may be insulated along atleast a portion of its length (e.g., with parylene, PTFE, etc.), withexposed portions permitting electrical communication with the currentgenerator 20 and the interventional element 100. For example, in someembodiments a distal portion of the guidewire may be exposed and theguidewire may be positioned at the treatment site such that the exposedportion of the guidewire is distal of the clot material CM. A proximalend of the guidewire may be coupled to the current generator such thatthe exposed portion of the guidewire functions as a return electrode. Insome embodiments, the guidewire may be coupled to the positive terminalof the power source and the exposed portion functions as a deliveryelectrode. The guidewire may be used as a delivery or return electrodewith any delivery or return electrode carried by any component of thetreatment system (e.g., one or more of the first-third catheters 14, 13,12, the interventional element 100, etc.).

FIGS. 4D-4F illustrate optional processes that may be performed before,during, and/or after deployment of the interventional element 100. Withreference to FIG. 4D, in some methods fluid F may be delivered to thetreatment site via the second catheter 13 and/or third catheter 12 whilecurrent is being delivered to the interventional element 100. Fluiddelivery may occur before or while the interventional element 100 isengaging the thrombus, and may coincide with the entire duration ofcurrent delivery or just a portion thereof.

FIG. 5 is a chart showing clot detachment forces for differentinterventional elements of the present technology under differentenvironmental conditions (as indicated along the x-axis). For theseexperiments, a blood clot was manufactured by mixing fibrinogen, blood,thrombin and calcium chloride. A representative interventional elementwas immersed or deployed in contact with the blood clot to mimicclinical deployment and positive charge was applied to it for aspecified duration. The whole assembly was immersed in blood and flowwas applied at 150 mL/min (“Flow”) or 0 mL/min (“No Flow”). Thecomposition of the manufactured blood clot and the parameters of theapplied energy (e.g., duration, amplitude, etc.) were generally the samefor all samples in both experiments. The assembly (blood clot andinterventional element) was then removed from the experimental setup andthe blood clot was detached from the interventional element using alap-shear test with an Instron. The detachment force was measured and isreported in FIG. 5 . As demonstrated by the chart shown in FIG. 5 , theinventors have observed that the presence of blood flow at the treatmentsite reduces adhesion between an electrically charged interventionalelement and a blood clot by approximately two-fold (see “NiTi (No Flow)”vs. “NiTi (Flow)”, and “NiTi+Gold (No Flow)” vs. “NiTi+Gold (Flow)”).).FIG. 5 also demonstrates that the adhesion forces for a gold-coatedinterventional element are at least two times the adhesion forces for anon-coated interventional element (see “NiTi (No Flow)” vs. “NiTi+Gold(No Flow)”, and “NiTi (Flow)” vs. “NiTi+Gold (Flow)”).

Although the presence of blood flow at the treatment site is believed toreduce adhesion between an electrically charged interventional elementand a blood clot, the inventors have also observed that infusion of afluid F having a higher ion concentration than blood increases theelectrical conductivity at the treatment site, thereby providing animproved environment for electrically enhanced clot adhesion as comparedto the presence of blood alone. The same experimental setup describedabove was used and the blood was replaced by saline with flow at 150mL/min. The inventors observed that the adhesive force was approximately35% higher when saline was infused at the treatment site than it was inthe presence of autologous blood alone. In some embodiments, infusion ofthe fluid F may occur in the presence of blood flow, or without bloodflow present (the latter condition being induced, for example, byinflation of the expandable element 401 on the first catheter 14).Suitable fluids include, for example, saline, contrast solution, andother fluids having a higher ion concentration than blood. Additionally,the delivery of fluid F at the treatment site may also reduce new clotformation on the interventional element 100, which may occur in thepresence of blood and direct or pulsatile electric current.

Referring now to FIG. 4E, in some instances aspiration may be applied tothe treatment site via the second catheter 13. For example, followingdeployment of the interventional element 100, the third catheter 12 canbe retracted and removed from the lumen of the second catheter 13. Thetreatment site can then be aspirated via the second catheter 13, forexample via a suction source such as a pump or syringe coupled to aproximal portion of the second catheter 13. In some embodiments,following expansion of the interventional element 100, the treatmentsite is aspirated concurrently with supplying electrical energy to theinterventional element 100 via the current generator 20. By combiningaspiration with the application of electrical energy, any newly formedclots (e.g., any clots formed that are attributable at least in part tothe application of electrical energy), or any clot pieces that arebroken loose during the procedure, can be pulled into the secondcatheter 13, thereby preventing any such clots from being releaseddownstream of the treatment site. As a result, concurrent aspiration maypermit the use of higher power or current levels delivered to theinterventional element 100 without risking deleterious effects of newclot formation. Additionally, aspiration can capture any gas bubblesformed along the interventional element 100 or marker band 220 (FIG. 2A)during application of electrical energy to the interventional element100, which can improve patient safety during the procedure.

In some embodiments, aspiration is applied while the interventionalelement 100 is retracted into the second catheter 13. Aspiration at thisstage can help secure the clot material CM within the second catheter 13and prevent any dislodged portion of the clot material CM from escapingthe second catheter 13 and being released back into the vessel V. Invarious embodiments, the treatment site can be aspirated continuouslybefore, during, or after delivering electrical signals to theinterventional element 100 as well as before, during, or afterretraction of the interventional element 100 into the second catheter13.

With reference to FIGS. 4B-4F, at any time before, during, and/or afterdeployment of the interventional element 100, a flow arrest element maybe deployed within the blood vessel proximal of the clot material CM topartially or completely arrest blood flow to the treatment site. Forexample, as shown in FIGS. 4B-4F, the first catheter 14 may be a balloonguide catheter having a balloon 401 at its distal portion. The balloon401 may be configured to inflate or expand into apposition with thesurrounding blood vessel wall, thereby at least partially arrestingblood flow distal to the balloon 401. In some embodiments, the flowarrest element can have other forms or configurations suitable forpartially or completely arresting blood flow within the vessel V.

In some methods, the flow arrest element may be deployed at a locationalong the blood vessel proximal of the clot material CM (for example, ata proximal portion of the internal carotid artery) and may remaininflated as the interventional element 100 is deployed and eventuallywithdrawn to remove the thrombus. For example, FIGS. 4B-4F show theballoon 401 blocking flow from a portion of the artery proximal of theballoon toward the interventional element 100 and treatment area, whilethe second catheter 13 and third catheter 12 are positioned at thetreatment site (FIG. 4B), while the interventional element 100 isexpanded within the clot material CM (FIG. 4C), while fluid is infusedat the treatment site (FIG. 4D), and while aspiration is applied at thetreatment site (FIG. 4E). Although the balloon 401 is shown in anexpanded state in each of FIGS. 4B-4F, it will be appreciated that theballoon 401 may be in an unexpanded state and/or deflated at any timethroughout the procedure to allow blood flow.

As shown in FIG. 4F, in some embodiments the flow arrest element may bea balloon 403 coupled to the second catheter 13 (such as a distal accesscatheter). In such embodiments, the first catheter 14 may not include aflow arrest element such that flow arrest is achieved via deployment ofthe flow arrest element coupled to the second catheter 13. For example,in such embodiments, the first catheter 14 may be a sheath or supportcatheter. The balloon 403 may be inflated at a location distal of thedistal end of the first catheter 14, closer to the thrombus. In somemethods, the flow arrest element may be deflated and inflated severaltimes throughout the procedure.

At least while the interventional element 100 is deployed and engagingthe thrombus CM, electric current may be delivered to the interventionalelement 100 to positively charge the interventional element 100, therebyenhancing clot adhesion to the interventional element 100. As previouslydiscussed with reference to FIG. 5 , the inventors have observedimproved electrically enhanced clot adhesion in the absence of bloodflow. As such, it may be especially beneficial to arrest flow (e.g., viaa flow arrest element on the first or second catheter 14, 13) while theinterventional element 100 is charged, and while expanding theinterventional element 100 within the thrombus and/or when withdrawingthe thrombus proximally.

With reference to FIG. 4G, while the interventional element 100 isengaged with the clot material CM, the clot material CM can be removed.For example, the interventional element 100, with the clot material CMgripped thereby, can be retracted proximally (for example, along withthe second catheter 13 and, optionally, the third catheter 12). Thesecond catheter 13, interventional element 100, and associated clotmaterial CM may then be withdrawn from the patient, optionally throughone or more larger surrounding catheters. During this retraction, theinterventional element 100 can grip the clot material CM electricallyand/or electrostatically, e.g., via the application of current from acurrent generator as discussed herein. (As used herein with reference togripping or retrieving thrombus or other vascular/luminal material, orto apparatus for this purpose, “electrical” and its derivatives will beunderstood to include “electrostatic” and its derivatives.) Accordingly,the interventional element 100 can maintain an enhanced or electricallyand/or electrostatically enhanced grip on the clot material CM duringretraction. In other embodiments, the current generator 20 may ceasedelivery of electrical signals to the interventional element 100 priorto retraction of the interventional element 100 with respect to thevessel V. In some embodiments, the interventional element 100 and clotmaterial CM form a removable, integrated thrombus-device mass whereinthe connection of the thrombus to the device is electrically enhanced,e.g. via the application of current as discussed herein.

FIGS. 6A-6B illustrates another method of removing clot material fromthe lumen of a blood vessel V using embodiments of the presenttechnology. As shown in FIG. 6A, a catheter 603 (such as second catheter13) may be advanced through a vessel V to a position adjacent to clotmaterial CM. The catheter 603 can be advanced through a surroundingcatheter 604, for example a balloon-guide catheter having a balloon 601or other element configured to expand into contact with the vessel wallto secure the catheter 604 in position against the wall of the vessel Vand/or to partially or completely arrest flow. In other embodiments, asurrounding sheath or support catheter can be used in place of thecatheter 604. In still other embodiments, the catheter 604 can beomitted and the catheter 603 can be advanced directly through the vesselV to the treatment site.

While in the position shown in FIG. 6A, negative pressure can besupplied to the catheter 603 to aspirate the area adjacent to the clotmaterial CM. For example, the catheter 603 can be fluidically coupled tothe suction source 25 (FIG. 1A) at a proximal portion of the catheter603. Additionally, electrical signals can be supplied to the catheter603 via the current generator 20 to electrically charge a distal portionof the catheter 603. For example, as described above with respect toFIG. 2A, in some embodiments the catheter 603 can be generally similarto second catheter 13 and can include a first electrode 206 disposed atits distal portion. The first electrode can be any electricallyconductive element, for example a conductive band extending around aninner or outer surface of the catheter 603, a stent engaged with aninner surface of the second catheter 603, etc. The first electrode canbe electrically coupled to a conductive lead that extends proximallyalong the catheter 603 and is coupled at its proximal end to thepositive terminal of current generator 20. The conductive lead can be,for example, a wire, coil, or other conductive element carried by and/orcoupled to the catheter 603. In some embodiments, the conductive lead isembedded within a wall of the second catheter 603. In other embodiments,the conductive lead is disposed along an external surface of thecatheter 603 (e.g., helically wound around the outer surface of thecatheter 603 along its length). The conductive lead can be covered withinsulative material along a portion of its length, for example parylene,PTFE, or other suitable insulative coating.

The negative terminal of the current generator 20 can be coupled to areturn electrode to complete the electrical circuit with the firstelectrode disposed on the catheter 603. In some embodiments, the returnelectrode can be an external electrode (e.g., a needle or a groundingpad coupled to the patient's skin). In other embodiments, the returnelectrode can be carried by a separate catheter, for example theelectrode 208 of the catheter 604 shown in FIG. 2A. In some embodiments,the return electrode can be carried by the catheter 603 at a positionspaced apart from the first electrode. For example, the first electrodecan be a conductive element such as a band or ring disposed at aposition spaced apart from the first electrode. In some embodiments, thefirst electrode may be exposed along a radially inner surface of thecatheter 603, while the return electrode may be exposed along a radiallyouter surface of the catheter 603. In some embodiments, the returnelectrode can be a separate expandable member coupled to an outersurface of the catheter 603 (e.g., the balloon 403 of FIG. 4G or otherexpandable member having a conductive element such as a metallic braidtherein).

When the first and second electrodes are coupled to the positive andnegative terminals, respectively, of the current generator 20, thedistal end of the catheter 603 becomes positively charged and attractsnegatively charged constituents in the blood and clot material CM. Thiselectrical attraction promotes movement of the clot material CM into thecatheter 603, adhesion of the clot material CM to the inner surface ofthe catheter 603, and retention of the clot material CM in the lumen ofthe catheter 603.

In various embodiments, aspiration can be performed via the catheter 603before, during, and/or after supplying electrical energy to the firstelectrode via the current generator 20. In some embodiments, theelectrical signals can continue to be applied while the catheter 603 andattached clot material CM are retracted proximally through the vessel Vtowards the catheter 604. In some embodiments, the current generator 20can cease to supply electrical signals to the first electrode, whilenegative pressure can continue to be supplied to the catheter 603.

In FIG. 6B, the clot material CM has been moved to at least partiallyenter the catheter 603. In some embodiments, the clot material CM cansubstantially block the lumen of the catheter 603, thereby creating a“corking” effect that may be noticeable to a clinician supplyingnegative pressure to the catheter 603. Once the catheter 603 is corkedwith the clot material CM, it becomes increasingly difficult to supplycontinued negative pressure to the catheter 603. This corking effect canindicate to a clinician that the clot material CM has been engaged bythe catheter 603 and that the clot material CM and catheter 603 can beretracted through the vessel V and into the catheter 604 or othersurrounding catheter. In some embodiments, the current generator 20 cancontinue to supply electrical signals to the catheter 603 and the returnelectrode during retraction, while in other embodiments the currentgenerator 20 can cease supplying electrical signals during retraction ofthe catheter 603 and the clot material CM.

IV. Select Embodiments of Waveforms for Electrically Enhanced Retrieval

FIGS. 7A-7E show various electrical waveforms for use with the treatmentsystems of the present technology. Although the waveforms and otherpower delivery parameters disclosed herein can be used with the devicesand methods described above with respect to FIGS. 1A-6B, the waveformsand other parameters are also applicable to other device configurationsand techniques. For example, the return electrode can be provided alongthe catheter wall, as a separate conductive member extending within thecatheter lumen, as a needle electrode provided elsewhere in the body,etc. In each of these device configurations, the power deliveryparameters and waveforms can be beneficially employed to promote clotadhesion without damaging surrounding tissue. Additionally, although thewaveforms and other power delivery parameters disclosed herein may beused for treating a cerebral or intracranial embolism, otherapplications and other embodiments in addition to those described hereinare within the scope of the technology. For example, the waveforms andpower delivery parameters disclosed herein may be used to electricallyenhance removal of emboli from body lumens other than blood vessels(e.g., the digestive tract, etc.) and/or may be used to electricallyenhance removal of emboli from blood vessels outside of the brain (e.g.,pulmonary blood vessels, blood vessels within the legs, etc.).

While applying a continuous uniform direct current (DC) electricalsignal (as shown in FIG. 7E) to positively charge the interventionalelement and/or aspiration catheter can improve attachment to thethrombus, this can risk damage to surrounding tissue (e.g., ablation),and sustained current at a relatively high level may also bethrombogenic (i.e., may generate new clots). For achieving effectiveclot-grabbing without ablating tissue or generating substantial newclots at the treatment site, periodic waveforms have been found to beparticularly useful. Without wishing to be bound by theory, theclot-adhesion effect appears to be most closely related to the peakcurrent of the delivered electrical signal. Periodic waveforms canadvantageously provide the desired peak current without deliveringexcessive total energy or total electrical charge. Periodic, non-squarewaveforms in particular are well suited to deliver a desired peakcurrent while reducing the amount of overall delivered energy or chargeas compared to either uniform applied current or square waveforms.

FIGS. 7A-7D illustrate various periodic waveforms that can be used withthe devices and methods described above with respect to FIGS. 1A-6B, aswell as with other devices and techniques. FIG. 7E illustrates acontinuous uniform DC electrical signal which can also be used in someembodiments. Referring to FIGS. 7A-7D, electrical power can be deliveredaccording to these waveforms as pulsed direct current. FIGS. 7A and 7Billustrate periodic square and triangular waveforms, respectively. Thesetwo waveforms have the same amplitude, but the triangular waveform isable to deliver the same peak current as the square waveform, with onlyhalf of the total charge delivered, and less total energy delivered.FIG. 7C illustrates another pulsed-DC or periodic waveform which is acomposite of a square waveform and a triangular waveform. Thissuperposition of a triangular waveform and a square waveform shown inFIG. 7C delivers additional efficacy compared to the triangular waveformof FIG. 7B while nonetheless delivering less overall energy than thesquare waveform of FIG. 7A. This is because the delivered energy isproportional to the square of current and the brief high peak in thecomposite waveform of FIG. 7C ensures that current is supplied withoutdispensing excessive energy. FIG. 7D illustrates yet another non-squarewaveform, in this case a trapezoidal waveform in which “ramp-up” and“ramp-down” portions at the beginning and end of each pulse provideperiods of reduced current compared to square waveforms. In otherembodiments, different non-square waveforms can be used, including asuperposition of a square waveform with any non-square waveform,depending on the desired power delivery characteristics.

The waveform shape (e.g., pulse width, duty cycle, amplitude) and lengthof time can each be selected to achieve desired power deliveryparameters, such as overall electrical charge, total energy, and peakcurrent delivered to the interventional element and/or catheter. In someembodiments, the overall electrical charge delivered to theinterventional element and/or catheter can be between about 30-1200 mC,or between about 120-600 mC. According to some embodiments, the totalelectrical charge delivered to the interventional element and/orcatheter may be less than 600 mC, less than 500 mC, less than 400 mC,less than 300 mC, less than 200 mC, or less than 100 mC.

In some embodiments, the total energy delivered to the interventionalelement and/or aspiration catheter can be between about 0.75-24,000 mJ,or between about 120-24,000 mJ, or between about 120-5000 mJ. Accordingto some embodiments, the total energy delivered to the interventionalelement and/or aspiration catheter may be less than 24,000 mJ, less than20,000 mJ, less than 15,000 mJ, less than 10,000 mJ, less than 5,000 mJ,less than 4,000 mJ, less than 3,000 mJ, less than 2000 mJ, less than1,000 mJ, less than 900 mJ, less than 800 mJ, less than 700 mJ, lessthan 600 mJ, less than 500 mJ, less than 400 mJ, less than 300 mJ, orless than 200 mJ, or less than 120 mJ, or less than 60 mJ, or less than48 mJ, or less than 30 mJ, or less than 12 mJ, or less than 6 mJ, orless than 1.5 mJ.

In some embodiments, the peak current delivered can be between about0.5-20 mA, or between about 0.5-5 mA. According to some embodiments, thepeak current delivered may be greater than 0.5 mA, greater than 1 mA,greater than 1.5 mA, greater than 2 mA, greater than 2.5 mA, or greaterthan 3 mA.

The duration of power delivery is another important parameter that canbe controlled to achieve the desired clot-adhesion effects withoutdamaging tissue at the treatment site or generating new clots. In atleast some embodiments, the total energy delivery time can be no morethan 1 minute, no more than 2 minutes, no more than 3 minutes, no morethan 4 minutes, or no more than 5 minutes. According to someembodiments, the total energy delivery time may be less about 30seconds, less than about 1 minute, less than about 90 seconds, or lessthan about 2 minutes. As used herein, the “total energy delivery time”refers to the time period during which the waveform is supplied to theinterventional element and/or catheter (including those periods of timebetween pulses of current).

The duty cycle of the applied electrical signal can also be selected toachieve the desired clot-adhesion characteristics without ablatingtissue or promoting new clot formation. In some embodiments, the dutycycle can be between about 5% about 99% or between about 5% to about20%. According to some embodiments, the duty cycle may be about 10%,about 20%, about 30%, about 40%, or about 50%. In yet other embodiments,a constant current may be used, in which the duty cycle is 100%. For100% duty cycle embodiments, a lower time or current may be used toavoid delivering excess total energy to the treatment site.

Table 1 presents a range of values for power delivery parameters ofdifferent waveforms. For each of the conditions set forth in Table 1, aresistance of 1 kohm and a frequency of 1 kHz (for the Square, Triangle,and Composite conditions) was used. The Constant conditions represent acontinuous and steady current applied for the duration, i.e. 100% dutycycle. The Peak Current 1 column represents the peak current for thecorresponding waveform. For the Composite conditions, the Peak Current 2column indicates the peak current of the second portion of the waveform.For example, referring back to FIG. 7C, Peak Current 1 would correspondto the current at the top of the triangular portion of the waveform,while Peak Current 2 would correspond to the current at the top of thesquare portion of the waveform.

TABLE 1 Total Total Energy Energy Peak Peak (@ (@ Current Current DutyDuty Peak Pulse Total R = 1000 R = 50 1 2 Cycle Cycle Voltage WidthTotal Charge ohm) ohm) Condition (mA) (mA) 1 (%) 2 (%) (V) (ms) Time (s)(mC) (mJ) (mJ) Constant 1 2 0 100 0 2 n/a 120 240 480 24 Constant 2 2 0100 0 2 n/a 60 120 240 12 Constant 3 10 0 100 0 10 n/a 60 600 6000 300Constant 4 20 0 100 0 20 n/a 60 1200 24000 1200 Constant 5 10 0 100 0 10n/a 120 1200 12000 600 Constant 6 1 0 100 0 1 n/a 120 120 120 6 Constant7 0.5 0 100 0 1 n/a 120 60 30 1.5 Constant 8 0.5 0 100 0 1 n/a 60 30 150.75 Square 1 10 0 10 0 10 0.1 120 120 1200 60 Square 2 4 0 50 0 4 0.5120 240 960 48 Square 3 20 0 10 0 20 0.1 120 240 4800 240 Square 4 20 010 0 20 0.1 60 120 2400 120 Square 5 10 0 10 0 10 0.1 60 60 600 30Triangle 1 10 0 10 0 10 0.1 120 60 1200 60 Triangle 2 20 0 10 0 20 0.1120 120 4800 240 Composite 1 20 1 10 20 20 0.3 120 144 4824 264Composite 2 10 2 10 20 10 0.3 120 108 1296 156

As seen in Table 1, the periodic waveforms (Square, Triangle, andComposite conditions) achieve higher peak currents with lower overallcharge delivered than the corresponding Constant conditions. Forexample, in condition Constant 4, a peak current of 20 mA corresponds toa total energy delivered of 24,000 mJ, while condition Square 3 deliversa peak current of 20 mA with a total energy of only 4,800 mJ. ConditionsTriangle 2 and Composite 1 similarly deliver lower total energy whilemaintaining a peak current of 20 mA. Since clot-adhesion appears to bedriven by peak current, these periodic waveforms can therefore offerimproved clot adhesion while reducing the risk of damaging tissue at thetreatment site or promoting new clot formation. Table 1 also indicatesthat the Triangle and Composite conditions achieve higher peak currentswith lower overall charge delivered than the corresponding Squareconditions. For example, condition Square 3 has a peak current of 20 mAand a total charge delivered of 240 mC, while condition Triangle 2 has apeak current of 20 mA but a total charge delivered of only 120 mC, andcondition Composite 1 has a peak current of 20 mA and a total chargedelivered of only 144 mC. As such, these non-square waveforms provideadditional benefits by delivering desirable peak current while reducingthe overall charge delivered to the treatment site.

Although Table 1 represents a series of waveforms with a singlefrequency (1 kHz), in some embodiments the frequency of the pulsed-DCwaveforms can be controlled to achieve the desired effects. For example,in some embodiments the frequency of the waveform can be between 1 Hzand 1 MHz, between 1 Hz and 1 kHz, or between 500 Hz to 1 kHz.

V. Conclusion

This disclosure is not intended to be exhaustive or to limit the presenttechnology to the precise forms disclosed herein. Although specificembodiments are disclosed herein for illustrative purposes, variousequivalent modifications are possible without deviating from the presenttechnology, as those of ordinary skill in the relevant art willrecognize. In some cases, well-known structures and functions have notbeen shown and/or described in detail to avoid unnecessarily obscuringthe description of the embodiments of the present technology. Althoughsteps of methods may be presented herein in a particular order, inalternative embodiments the steps may have another suitable order.Similarly, certain aspects of the present technology disclosed in thecontext of particular embodiments can be combined or eliminated in otherembodiments. Furthermore, while advantages associated with certainembodiments may have been disclosed in the context of those embodiments,other embodiments can also exhibit such advantages, and not allembodiments need necessarily exhibit such advantages or other advantagesdisclosed herein to fall within the scope of the present technology.Accordingly, this disclosure and associated technology can encompassother embodiments not expressly shown and/or described herein.

Throughout this disclosure, the singular terms “a,” “an,” and “the”include plural referents unless the context clearly indicates otherwise.Similarly, unless the word “or” is expressly limited to mean only asingle item exclusive from the other items in reference to a list of twoor more items, then the use of “or” in such a list is to be interpretedas including (a) any single item in the list, (b) all of the items inthe list, or (c) any combination of the items in the list. Additionally,the terms “comprising” and the like are used throughout this disclosureto mean including at least the recited feature(s) such that any greaternumber of the same feature(s) and/or one or more additional types offeatures are not precluded. Directional terms, such as “upper,” “lower,”“front,” “back,” “vertical,” and “horizontal,” may be used herein toexpress and clarify the relationship between various elements. It shouldbe understood that such terms do not denote absolute orientation.Reference herein to “one embodiment,” “an embodiment,” or similarformulations means that a particular feature, structure, operation, orcharacteristic described in connection with the embodiment can beincluded in at least one embodiment of the present technology. Thus, theappearances of such phrases or formulations herein are not necessarilyall referring to the same embodiment. Furthermore, various particularfeatures, structures, operations, or characteristics may be combined inany suitable manner in one or more embodiments.

We claim:
 1. A thrombectomy system, comprising: a first catheter havinga distal portion configured to be positioned adjacent to a thrombus in ablood vessel; a second catheter, the first catheter configured to beslidably disposed within a lumen of the second catheter; a thirdcatheter, the second catheter configured to be slidably disposed withina lumen of the third catheter; an electrode coupled to the firstcatheter and configured to be disposed distal to the second catheter,the electrode configured to be electrically coupled to an extracorporealpower supply; and an interventional element configured to be deliveredthrough a lumen of the first catheter, the interventional elementcomprising an expandable member configured to be electrically coupled tothe extracorporeal power supply.
 2. The system of claim 1, wherein theelectrode is in electrical communication with a conductive leadextending proximally along the first catheter.
 3. The system of claim 1,wherein the electrode comprises a conductive band extending at leastpartially circumferentially around the distal portion of the firstcatheter.
 4. The system of claim 3, wherein the conductive band isdisposed on an inner surface of the first catheter.
 5. The system ofclaim 2, wherein the conductive band is disposed on an outer surface ofthe first catheter.
 6. The system of claim 1, further comprising a powersupply having positive and negative terminals, the electrode beingcoupled to the negative terminal and the interventional element beingcoupled to the positive terminal.
 7. The system of claim 1, wherein,when the interventional element and the electrode are in the presence ofan electrolytic medium and voltage is supplied via the extracorporealpower supply, current flows from the interventional element to theelectrode.
 8. The system of claim 1, wherein a proximal end of theinterventional element is coupled to a distal end of a core member, thecore member extending proximally through the first catheter.
 9. Thesystem of claim 1, wherein the interventional element comprises athrombectomy device.
 10. The system of claim 1, wherein theinterventional element comprises a laser-cut stent or a mesh.
 11. Asystem, comprising: an expandable thrombectomy device coupled to adistal end of an elongate shaft, the shaft configured to be electricallycoupled to a first terminal of a power supply; a first elongate tubularmember configured to receive the shaft therethrough, the first tubularmember having a conductive lead extending along a length of the firsttubular member and configured to be electrically coupled to a secondterminal of the power supply; an electrode electrically coupled to theconductive lead; a second elongate tubular member having a lumenconfigured to slidably receive the first tubular member therethrough;and a third elongate tubular member having a lumen configured toslidably receive the second tubular member therethrough.
 12. The systemof claim 11, wherein the shaft comprises a conductive element inelectrical communication with the expandable thrombectomy device. 13.The system of claim 11, wherein the electrode comprises a conductiveband extending at least partially circumferentially around a distalportion of the first tubular member.
 14. The system of claim 13, whereinthe conductive band is disposed on an inner surface of the first tubularmember.
 15. The system of claim 13, wherein the conductive band isdisposed on an outer surface of the first tubular member.
 16. The systemof claim 11, wherein the first tubular member comprises an aspirationcatheter.
 17. The system of claim 11, further comprising a suctionsource configured to supply negative pressure through the first tubularmember to aspirate a region adjacent to a distal portion of the firsttubular member.
 18. The system of claim 11, wherein the first tubularmember is an aspiration catheter having a proximal portion configured tobe fluidically coupled to a suction source.
 19. The system of claim 11,wherein the thrombectomy device comprises a stent retriever.
 20. Thesystem of claim 11, wherein the thrombectomy device comprises alaser-cut stent or a mesh.